Which ever format you have the most of – go with that one.
If P2 is the majority of the footage then start there.
Your go pro clips may be of smaller size. You’ll need to res them up or put them over a background.
Have you tried creating an all new proj?
You have enough hard drive space for renders right?
Next would be Adobe Tech support or re-installing the app.
You have to “De-activate” it before un-installing it. FYI
Chris Tompkins
Video Atlanta LLC