Slitherine

Playing as Dragonhold and getting the same diplomacy bug i got when playing as Sonneneve and Aevinwode - lots of kingdoms i've never even had a border with are at Minus 50 diplomatic rating to me and reasons are listed as 'Annexed Province' and 'Occupying Capital' (and even more weirdly the first is a much bigger negative to their attitude than the second).

Can send the saved game if anyone gives me the email address to send it to.

Edit - it's now turned up on the Galeni, who i was backing to be the new Imperial power, so no chance of completing the campaign objectives as a result

Whenever you try and conquer loads of provinces including capitals your diplomatic rating will be at -50 for a dramatic long time (I believe 1 or 2 points per turn???), but if you are on a conquering rampage I doubt diplomacy will be of much use anyway.

At least the 2 you mention are only termporary and fade with time (loads of time), actually annexing a capital will give you a permanent drop in rating.

Hadn't annexed any capitals at all in that game - was careful not to - but had a -7 to -9 penalty with lots of factions saying "annexed capital" and then huge penalties saying "annexed province" with lots of kingdoms i'd never even had a border with. And happens in every game