I haven’t used the program much since I posted the problem, but just opened it and tried to replicate, and was unable to make it crash. I don’t think I’ve updated Shotcut recently. But when I had the problem, I may have had more windows/programs open which could have created a memory problem.
It might be helpful if the zoom, position etc. text boxes were not so responsive. If I click in the zoom and start typing “140%”, as soon as I type the “1” the program resizes the video to 1%, then again to 14% when I type the “4”, etc. I hear my computer fan spin up with all that resizing and it may have caused the crash earlier. Maybe the text boxes could be made to register only once you’ve hit Enter or clicked away from the box.