Did you find a fix for this? I recorded a 30min long video and it was also stuck on processing. Even a 10min long video just kept processing. I really need this to work. This is one of those times I wish there was a screen mirroring app that didn't require USB debugging, because then I could mirror my screen to my computer, and use OBS Studio to record everything. But if anyone has a fix for long screen recordings not processing, let me know please!