Gyan
You are going to have to provide specific info for each of your issues. And this is best done at the bug tracker.
The latest commit of harfbuzz leads to this breakage. You should peg harfbuzz to c4c8eb4f8c
@dm-de test with my [full build](https://github.com/GyanD/codexffmpeg/releases/tag/2025-09-04-git-2611874a50). If it works (does here), then it's a build issue.
Then it looks like an issue with your setup. Try running it a few times, with both gpu off and on. I've had reports of ffmpeg getting stuck on first...
'doesn't work' is vague. What happens? Which version of ffmpeg? Which version of Opentoonz?
So this needs to be directed to Opentoonz first to obtain the error logs or any other diagnostic information about the dialog box contents. Can't proceed without that.