This is the session I use to recreate the crash. To this session I add a 4th loop and click on the "sync" mark before I start recording. BTW, I tried to upload the file, but your forum program would not allow a file with the ext .slsess to upload.
<?xml version="1.0"?>
<SLSession version="1.6.14">
<Globals tempo="121.1020205" eighth_per_cycle="128" common_dry="0" common_wet="1" input_gain="1" sync_source="1" auto_disable_latency="1" jack_timebase_master="0" output_midi_clock="0" use_midi_start="0" use_midi_stop="0" send_midi_start_on_trigger="0" smart_eighths="1"/>
<Loopers>
<Looper index="0" channels="2" loop_secs="40" discrete_io="no" use_common_ins="yes" use_common_outs="yes" relative_sync="no" auto_latency="yes" tempo_stretch="yes" stretch_ratio="1" pitch_shift="0" loop_audio="/home/sczjd/Music/sooperlooper/sl-02-18-10.slsess_loop_00.wav">
<Panner linked="no" link_direction="0" bypassed="no">
<StreamPanner x="0.280000" type="Equal Power Stereo" muted="no"/>
<StreamPanner x="0.820000" type="Equal Power Stereo" muted="no"/>
<Output x="0.000000" y="0.000000"/>
<Output x="1.000000" y="0.000000"/>
</Panner>
<Controls>
<Control name="rec_thresh" value="0.012401501648128032684"/>
<Control name="dry" value="0"/>
<Control name="wet" value="1"/>
<Control name="feedback" value="1"/>
<Control name="rate" value="1"/>
<Control name="scratch_pos" value="0"/>
<Control name="delay_trigger" value="0"/>
<Control name="use_feedback_play" value="0"/>
<Control name="quantize" value="3"/>
<Control name="round" value="0"/>
<Control name="redo_is_tap" value="0"/>
<Control name="sync" value="1"/>
<Control name="use_rate" value="0"/>
<Control name="fade_samples" value="64"/>
<Control name="playback_sync" value="0"/>
<Control name="use_safety_feedback" value="1"/>
<Control name="input_latency" value="1024"/>
<Control name="output_latency" value="4096"/>
<Control name="trigger_latency" value="1024"/>
<Control name="mute_quantized" value="0"/>
<Control name="overdub_quantized" value="0"/>
<Control name="round_integer_tempo" value="0"/>
</Controls>
</Looper>
<Looper index="1" channels="2" loop_secs="40" discrete_io="no" use_common_ins="yes" use_common_outs="yes" relative_sync="no" auto_latency="yes" tempo_stretch="yes" stretch_ratio="1" pitch_shift="0" loop_audio="/home/sczjd/Music/sooperlooper/sl-02-18-10.slsess_loop_01.wav">
<Panner linked="no" link_direction="0" bypassed="no">
<StreamPanner x="0.820000" type="Equal Power Stereo" muted="no"/>
<StreamPanner x="0.420000" type="Equal Power Stereo" muted="no"/>
<Output x="0.000000" y="0.000000"/>
<Output x="1.000000" y="0.000000"/>
</Panner>
<Controls>
<Control name="rec_thresh" value="0.0087151518091559410095"/>
<Control name="dry" value="0"/>
<Control name="wet" value="1"/>
<Control name="feedback" value="1"/>
<Control name="rate" value="1"/>
<Control name="scratch_pos" value="0"/>
<Control name="delay_trigger" value="0"/>
<Control name="use_feedback_play" value="0"/>
<Control name="quantize" value="3"/>
<Control name="round" value="0"/>
<Control name="redo_is_tap" value="0"/>
<Control name="sync" value="1"/>
<Control name="use_rate" value="0"/>
<Control name="fade_samples" value="64"/>
<Control name="playback_sync" value="1"/>
<Control name="use_safety_feedback" value="1"/>
<Control name="input_latency" value="1024"/>
<Control name="output_latency" value="4096"/>
<Control name="trigger_latency" value="1024"/>
<Control name="mute_quantized" value="0"/>
<Control name="overdub_quantized" value="0"/>
<Control name="round_integer_tempo" value="0"/>
</Controls>
</Looper>
<Looper index="2" channels="2" loop_secs="40" discrete_io="no" use_common_ins="yes" use_common_outs="yes" relative_sync="no" auto_latency="yes" tempo_stretch="yes" stretch_ratio="1" pitch_shift="0" loop_audio="/home/sczjd/Music/sooperlooper/sl-02-18-10.slsess_loop_02.wav">
<Panner linked="no" link_direction="0" bypassed="no">
<StreamPanner x="0.220000" type="Equal Power Stereo" muted="no"/>
<StreamPanner x="0.880000" type="Equal Power Stereo" muted="no"/>
<Output x="0.000000" y="0.000000"/>
<Output x="1.000000" y="0.000000"/>
</Panner>
<Controls>
<Control name="rec_thresh" value="0.025458224117755889893"/>
<Control name="dry" value="0"/>
<Control name="wet" value="1"/>
<Control name="feedback" value="1"/>
<Control name="rate" value="1"/>
<Control name="scratch_pos" value="0"/>
<Control name="delay_trigger" value="0"/>
<Control name="use_feedback_play" value="0"/>
<Control name="quantize" value="3"/>
<Control name="round" value="0"/>
<Control name="redo_is_tap" value="0"/>
<Control name="sync" value="1"/>
<Control name="use_rate" value="0"/>
<Control name="fade_samples" value="64"/>
<Control name="playback_sync" value="1"/>
<Control name="use_safety_feedback" value="1"/>
<Control name="input_latency" value="1024"/>
<Control name="output_latency" value="4096"/>
<Control name="trigger_latency" value="1024"/>
<Control name="mute_quantized" value="0"/>
<Control name="overdub_quantized" value="0"/>
<Control name="round_integer_tempo" value="0"/>
</Controls>
</Looper>
<Looper index="3" channels="2" loop_secs="40" discrete_io="no" use_common_ins="yes" use_common_outs="yes" relative_sync="no" auto_latency="yes" tempo_stretch="no" stretch_ratio="1" pitch_shift="0">
<Panner linked="no" link_direction="0" bypassed="no">
<StreamPanner x="0.000000" type="Equal Power Stereo" muted="no"/>
<StreamPanner x="1.000000" type="Equal Power Stereo" muted="no"/>
<Output x="0.000000" y="0.000000"/>
<Output x="1.000000" y="0.000000"/>
</Panner>
<Controls>
<Control name="rec_thresh" value="0"/>
<Control name="dry" value="0"/>
<Control name="wet" value="1"/>
<Control name="feedback" value="1"/>
<Control name="rate" value="1"/>
<Control name="scratch_pos" value="0"/>
<Control name="delay_trigger" value="0"/>
<Control name="use_feedback_play" value="0"/>
<Control name="quantize" value="3"/>
<Control name="round" value="0"/>
<Control name="redo_is_tap" value="0"/>
<Control name="sync" value="0"/>
<Control name="use_rate" value="0"/>
<Control name="fade_samples" value="64"/>
<Control name="playback_sync" value="0"/>
<Control name="use_safety_feedback" value="1"/>
<Control name="input_latency" value="1024"/>
<Control name="output_latency" value="4096"/>
<Control name="trigger_latency" value="1024"/>
<Control name="mute_quantized" value="0"/>
<Control name="overdub_quantized" value="0"/>
<Control name="round_integer_tempo" value="0"/>
</Controls>
</Looper>
<Looper index="4" channels="2" loop_secs="40" discrete_io="no" use_common_ins="yes" use_common_outs="yes" relative_sync="no" auto_latency="yes" tempo_stretch="no" stretch_ratio="1" pitch_shift="0">
<Panner linked="no" link_direction="0" bypassed="no">
<StreamPanner x="0.000000" type="Equal Power Stereo" muted="no"/>
<StreamPanner x="1.000000" type="Equal Power Stereo" muted="no"/>
<Output x="0.000000" y="0.000000"/>
<Output x="1.000000" y="0.000000"/>
</Panner>
<Controls>
<Control name="rec_thresh" value="0"/>
<Control name="dry" value="0"/>
<Control name="wet" value="1"/>
<Control name="feedback" value="1"/>
<Control name="rate" value="1"/>
<Control name="scratch_pos" value="0"/>
<Control name="delay_trigger" value="0"/>
<Control name="use_feedback_play" value="0"/>
<Control name="quantize" value="3"/>
<Control name="round" value="0"/>
<Control name="redo_is_tap" value="0"/>
<Control name="sync" value="0"/>
<Control name="use_rate" value="0"/>
<Control name="fade_samples" value="64"/>
<Control name="playback_sync" value="0"/>
<Control name="use_safety_feedback" value="1"/>
<Control name="input_latency" value="1024"/>
<Control name="output_latency" value="4096"/>
<Control name="trigger_latency" value="1024"/>
<Control name="mute_quantized" value="0"/>
<Control name="overdub_quantized" value="0"/>
<Control name="round_integer_tempo" value="0"/>
</Controls>
</Looper>
<Looper index="5" channels="2" loop_secs="40" discrete_io="no" use_common_ins="yes" use_common_outs="yes" relative_sync="no" auto_latency="yes" tempo_stretch="no" stretch_ratio="1" pitch_shift="0">
<Panner linked="no" link_direction="0" bypassed="no">
<StreamPanner x="0.000000" type="Equal Power Stereo" muted="no"/>
<StreamPanner x="1.000000" type="Equal Power Stereo" muted="no"/>
<Output x="0.000000" y="0.000000"/>
<Output x="1.000000" y="0.000000"/>
</Panner>
<Controls>
<Control name="rec_thresh" value="0"/>
<Control name="dry" value="0"/>
<Control name="wet" value="1"/>
<Control name="feedback" value="1"/>
<Control name="rate" value="1"/>
<Control name="scratch_pos" value="0"/>
<Control name="delay_trigger" value="0"/>
<Control name="use_feedback_play" value="0"/>
<Control name="quantize" value="3"/>
<Control name="round" value="0"/>
<Control name="redo_is_tap" value="0"/>
<Control name="sync" value="0"/>
<Control name="use_rate" value="0"/>
<Control name="fade_samples" value="64"/>
<Control name="playback_sync" value="0"/>
<Control name="use_safety_feedback" value="1"/>
<Control name="input_latency" value="1024"/>
<Control name="output_latency" value="4096"/>
<Control name="trigger_latency" value="1024"/>
<Control name="mute_quantized" value="0"/>
<Control name="overdub_quantized" value="0"/>
<Control name="round_integer_tempo" value="0"/>
</Controls>
</Looper>
</Loopers>
</SLSession>
