Playing without SWMH as I intend to convert to EU4:
I created a character to play as, a Siculo-Arabic Hurufi-Moslem in Sicily. Right now, it's been about 100, 120 years so (around 1175) and I've, so far, managed to convert Rome and another 9 or so provinces to Hurufi, as well as create the Hurufi Caliphate (one reason I chose this heresy)
One problem: Shia has about 4 provinces, I have about 10. However, Hurufi is still considered a Heresy of Shia Islam.
It was my understanding that you only needed to have 5 more provinces than your parent-religion to usurp them as the base religion?
I'm not entirely sure what's going on here, whether it's a vanilla bug or a HIP bug, or if the fact that I created the Caliphate first is bugging it, or whether it's WAD and you just took out (for whatever ungodly reason) the heresy-parent switching mechanic, or whether you just changed the requirements, I don't know, I couldn't find any information on switching at all, let alone any changes made or previous bug-reports...