I found a few problems in your project:
- The track height is very high. I suppose that could be a problem with your system and GPU memory. I will add a limit to this in a near future version to prevent problems. Here is your file with that change: updated version - corrected1.mlt (352.5 KB)
- Your project frame rate is weird: 30.018804. That should not cause a problem but I suppose it could. It is a sign that you are using Video Mode = Automatic and video with variable frame rate (common problem from screen capture software). Variable frame rate is not supported, but it does not usually cause this sort of problem but rather problems with accurate seeking on edits and A/V sync. Here is your project with the previous change plus changed to 30 fps.: updated version - corrected2.mlt (352.5 KB)
- You are using a slightly old version 20.07 and making heavy usage of the Crop: Rectangle filter. In older versions, that filter used a web technology to power that filter. That technology caused problems and has been removed. If you open this project in a new version (I suggest you try the beta), Shotcut automatically converts these filters to their new technology replacement.