I think I have this same issue too. And I noticed it just now after I've downloaded/spent 14 out of my 30 downloads quota.. (almost 250GB!)
If I recall correctly there has been an issue with the non-AI alpha PT in the past too. I had to append "_ALPHA" before the ".mp4" extension for some videos, and I had issues streaming via DLNA, so I had to copy the video internally on my headset for it to work the same way when I was streaming it. That was recently fixed, and it's not the same issue with AI alpha PT as I see it.
Now with this new AI alpha PT, I've been trying to figure out what's going wrong for at least an hour, and I'm still confused. When I enable the PT option, I just get a very transparent image and it's impossible even to see what is happening. I only see that the "Alpha" option is enabled, but not "Alpha AI" which I see when streaming videos.
So, will I be able to watch these downloaded videos when the issue is fixed, or will I have to redownload them all over again? I still cannot see what is that the app is doing on top of the AI alpha PT videos that I'm streaming, compared to the same ones that I'm downloading right now. There should be an easy fix to make the app treat these local videos the same way as the ones that we're streaming. Or not?
EDIT: in the meantime, I did find videos that somehow worked (but only via DLNA for some weird reason), but other ones I had to delete as they were unusable. I still don't see a pattern for why some videos would work, but at least I have locally some of them (about every third). I'm aware this AI alpha PT is in beta, and that the app might not work perfectly for all supported platforms, but I think features should be tested better before release, especially if you offer them to members who are paying for the service. There's no point in downloading (and wasting time) for something that doesn't work the same way as if it was streamed. Paying more to my ISP, and decreasing the already limited download quota here on SLR is not what I had in mind.