I reproduce it now on Flatpak too! Maybe before when I tested it I used a test build (pre alpha) on Qt 6. So, I think the problem is somehow related to the patches included in Qt 5.15.8 that this flatpak runtime uses it. Other builds use Qt 5.15.3. I do not have very detailed (specific Qt revision) control on flatpak. The manifest says `runtime-version: ‘5.15-21.08’. As you can see, that kind of rolls along with minor Qt releases under it. This flatpak runtime version was last updated in Shotcut version 22.03. I can make an updated alpha version that fixes quite a few things…
Updated alpha (Qt6) flatpak build here:
I will make a Qt 5.15.8 build and try to reproduce and fix it on the Shotcut master branch on my development system…
I was able to try that but unable to get it working. I will push the next beta to flathub when it becomes available at the end of the month.