Can't Add Province to the HRE

[Rocketbobcat]

Hi everyone,

I have attempted to find solutions to this through other threads, but none seemed to solve the problem and the only other one that seemed to have the same problem (about Trade Company and Add to HRE buttons overlapping) had no responses.

First, some details about my game: I'm running the most recent patch with the following DLC:
-Art of War
-Mandate of Heaven
-Dharma
-El Dorado
-Common Sense
-Rights of Man

and the following Mods:
-Graphical Map Improvements
-Graphical Map Improvements - Terrain Shadows


I am playing as Austria and am the Emperor of the HRE. The year is 1590, and I have passed all the reforms through "Revoke the Privelegia". I recently beat the Ottomans in a war and am attempting to add some provinces to the HRE so I can release Bulgaria, Corfu and Byzantium as HRE vassals (adding their capitals first). I have cored the provinces I want to add and they are adjacent to HRE provinces as Albania and Serbia are in the HRE, but I can't seem to add the new provinces to the HRE. The place where the HRE button normally is just has "add to trade company" and the HRE menu doesn't let me add any provinces through the "Add all provinces" option. I have previously been able to add non-state cores and territorial cores to the HRE (Ragusa and Anacona) and added Albania and Serbia's capitals to the HRE through connecting them to Ragusa before releasing them, but I can't seem to do it this time. What am I missing?

I have attached some pictures in case they prove helpful:

Spoiler: Kostendil -Political view

Spoiler: Kostendil -HRE view

Spoiler: HRE Menu

Thanks for the help!

 

[Kanem Bornu]

You cannot add non-Christian provinces to the HRE.

When a province becomes eligible to be added to the HRE (like when you convert that province), the button will change from add to trade company to add to HRE.

 

[Rocketbobcat]

You cannot add non-Christian provinces to the HRE.

When a province becomes eligible to be added to the HRE (like when you convert that province), the button will change from add to trade company to add to HRE.

Thank you so much!
First time playing HRE, never realized a province's religion played a role in HRE eligibility!