Heir with foreign religion ineligible under Elective Gavelkind?

[shivan]

My son and only heir was converted to tengri (I was reformed norse), and suddenly i had no heir.
Its not really listed anywhere in the UI and the wiki, but seems like it might be the reason.
When he converted back I had an heir again.

Anyone else experienced this?

 

[Dragatus]

IT looks like your vassals didn't want to vote for a heathen and preferred to abstain from voting.

 

[shivan]

I dont think thats it. I tried to click nominate and no one was there.

 

[Sergeant Flutter]

What is your government type? Culture?

 

[Thrake]

I have seen AI realms with rulers of different (pagan) religions so it must be something else.