"Your subjet rejected..." - no get rid of it, it's stupid

[Trin Tragula]

There's a known bug which makes annexation progress abort instead of stalling due to occupation. We are aware of that and looking into it.

you literally cannot integrate PUs as non christians. I've reported this for so long but nobody cares.

This is a separate thing. I would be very interested in how you get those PU's the game is not supposed to let you have those as a non-christian.

At least a few patches ago there was event, which could give you PU (even for non-Christian religion) if you shared dynasty. And keeping PU after religion switch (IMO) is second legitimate way to have PU as non-Christian.

That was a bug and fixed

They also went to the trouble of cloning any historical non-Christian ruler who had a PU.

There was only one such instance in the game as far as I'm aware.