IIRC you can only change your religion by decision once per lifetime. You already converted to Sunni.
Another thread already brought this up recently. Not sure what my opinion on the matter is. If you could change your religion even every 100 years it would be a very powerful tool and allow you to do very strange things. Like being Crusader, Saoshyant and Fylkir at the same time.
No, there is no limit on how many times you can change religion.
You need to be independent (or have a liege of a different religion), you can't be a nomad, your capital needs to have a different religion than you, you can't be of an Indian religion (because they have their own religion swapping decision), you can't be the head of your religion (caliph, Fylkir), you can't be a holy order (or AI in general), you must have the Rajas of India DLC, and you need 1000 Prestige in order to convert to a different religious group (or 500 to convert to another religion within the same religious group). And if you're the Byzantine emperor in the CM start you can't do this but have to use the Renounce Iconoclasm special decision instead.
Code:
convert_to_local_religion = {
only_playable = yes
potential = {
ai = no
is_playable = yes
is_nomadic = no
capital_scope = {
NOT = { religion = ROOT }
}
OR = {
independent = yes
liege = {
NOT = { religion = ROOT }
}
}
# The Indian religions can convert to each other anyway
OR = {
NOT = { religion_group = indian_group }
capital_scope = {
NOT = { religion_group = indian_group }
}
}
controls_religion = no
holy_order = no
has_dlc = "Rajas of India"
NOT = {
AND = {
has_dlc = "Charlemagne"
has_landed_title = e_byzantium # May instead renounce iconoclasm
has_landed_title = c_byzantion
religion = iconoclast
capital_scope = { religion = orthodox }
}
}
}
allow = {
OR = {
AND = {
prestige = 500
capital_scope = {
religion_group = ROOT
}
}
AND = {
prestige = 1000
capital_scope = {
NOT = { religion_group = ROOT }
}
}
}
}
My guess would be that the issue in this specific case is probably either insufficient prestige or that the liege was Sunni too.