I'm not really sure what it could be. I'm using OpenSeeFace for the facetracking, which is the same backend VSeeFace uses. Have you tried messing with any of the tracking settings? (Smoothing, tracking quality, etc)
(Sorry for the late reply)
Yes, I have tried to mess with the tracking settings and after a while I kiiiinda found some settings that made it a little better, but don't really seem to stop the issue. VSeeFace works fine tho, so that's weird...
It feels like the tracking is getting lost at times, and after a while it finds it again and works very well until all of a sudden the model comes to a halt and just kinda stays there as if it had lost tracking and was trying to figure out what to do
I can record a video of the issue if that helps somehow