So the short of it is - I broke my Brother (Nusun) - the elder.
All was well, he accepted all the roles I wanted to assign to him via the Clan -> Party UI. But all that changed after I made him Governor of a Castle. Things were odd in that interface as well - after I gave my brother the job. More to that later.
so I am on e1.5.9 (no mods)
After I took my Brother back into the Party (since the Castle can now manage without him, and I needed his party size boost back) I cannot assign him any roles from the Clan UI - Party members screen. No role at all. for him, the current role (None) or after talking to him privately he took up Quartermaster again is just stuck. when you click it you get the sound, but no menu. cant change the role. This persists even after changing his position by dragging him around in the Party screen, higher than other companions. Even immediately following me.
After I gave him all the roles (through talking with him) when I tab the others, the Interface shows ( None ) and the option [ None ] appears below that. But again for Nusun, only the last assigned Role shows, and no drop down when tapping. Removing all roles from him (again through talking) did not change the problem, still no drop down for him on the Clan UI- Party Member screen. (At least when he is Quartermaster, I do get his Party Size bonus)
I gave him his own party, then ordered it to disband. when I met him outside of the city gates, I asked to join me again. Still cannot assign roles via the UI, only through talking.
Now to the Governor UI. When you assign a character Governor, you can still go back and change it and before you do that see a list of all the people you have available to be the Governor, and hover over their images and compare their stats.
But when Nusun is Governor, his Avatar does not appear in the list of the available people. So you cant inspect his settings. Only if you first take him back into your party, he then appears as eligible selection.
To see this, you first have to make Nusun the Governor and then leave the settlement. When you come back and manage the castle, and change governor he is not listed in the available choices anymore.
I have a Save Game "Nusun" if that would be helpful (this is withhim no longer Governer, and not Quartermaster)