Shotcut version 21.05.01
Split a clip. Apply the Time Remap filter on the clip to the left. Change the Image Mode to Blend. Go to about a second before the end of the clip before it crosses into the clip on the right that does not have Time Remap. Put the mouse under the clip at the line where the playhead is, press play and keep the playhead at the spot where the playhead was at. After about a second after the playhead crosses into the clip on the right, click on the mouse to bring the playhead back to the clip on the left with Time Remap. Right when the playhead comes back press either F7 or F8 to turn Preview Scaling on to 360p or 540p. Shotcut will crash.
I’ve been testing this many, many times and the timing of this seems to be very specific for this to cause a crash. But after getting the timing down I can get it to crash almost every time.
Please see the demo here to understand best. I play the same section twice with the Image Mode on Nearest on the left clip. Then I switch to Blend. I play the section again then after a second into the clip on the right I click on the mouse to bring the playhead back and switch to 360p Preview Scaling. Then Shotcut crashes. This has also can happen with 540p Preview Scaling.