You lose your entire empire if you convert from christianity when starting the game as a archbishop even if you change government type

[MidasGold]

Started as the preset bishop near the vikings in the early start date, slowly founded a dynasty, built up my theocratic land to a small kingdom, converted to fuedal, took over scandinava, founded the hre, eventually conquered the byzantines, decided to found rome. took the hellenic option for fun, and lo and behold, the papalcy took away my bishiop province, stripping me of my entire empire. except i dont have a bishop province, it is not in my list of lands, i cant even hold it because im on my 6th ruler in my dynasty, and we havent been theocratic for at least three.

after faffing around, i found destroying the duchy title i started the game with, despite my character not holding it anymore, was a work around. Still, it doesnt make sense.