Strange behavior on layers

I’m running Shotcut 20.4.12 on Win10. I have an 8-core processor running at 3.20 GHz with 16G of RAM (so there should be plenty of power for this project). I’ve come up with a problem that I can’t figure out.

I’m running three tracks like this:

Top: jpeg files (square format) that sequence in and out in a slideshow fashion. Video fade in/out filters applied.
Middle: B-roll, 1920x1080 30fps mp4 file. No filters applied.
Bottom: Audio track (mp3). No filters applied.

Here’s the problem: When the .jpg fades in (top layer), the video file below (visible on either side of the square .jpg file) will start flickering. It stops flickering after the .jpg file fades out again.

I wasn’t able to work through it, and ended up resorting to VideoPad, which is a free (but non-FOSS) video editor. I set it up the exact same way there and was able to successfully complete the project.

Any idea what’s going on? I’m more than happy to take the learning experience, but I’m wondering if there is a legitimate bug here as the problem doesn’t pop up in a different application when executed in a similar fashion.

I can provide screenshots and other information later on if needed, I’m just on a different computer right now. TIA.

Is this in preview or export? If export, does it still do that if you disable parallel processing in Export > Video?

It happens in both preview and export. I wasn’t aware of the parallel processing option, so I will look at that later today and report back here.

I have not reproduced the problem from this description. I assume you turned on “Adjust opacity” in each of the fade in and out filters. These are the only video filters I used and no transitions.

I’ll look at it a little later and report back, probably within a few hours. Thanks for taking a look at this.

This was it exactly. When I turned on the ‘Adjust opacity’ feature that flickering problem went away. Thanks for the help on this. I’ll know for next time.