can't export video iPad

It's impossible to export a video on my iPad (9th gen). I have three projects and none of them can be exported because when I try to export them, I get a simple message: "it can't be processed successfully." (translation from Spanish)

I have tried different resolutions, app restart, device reboot, etc. I don't have any logs at all. I don't know what I can try.

I have 15GB of free memory on my iPad.

At least, I would like to export my project to another application.