Here's a good one. I'm playing as the Nakalim with nine other AI players, and am at that stage of the game where several alliance groups are being formed. The alliance I'm a part of declares war on the Vodyani (blue colour) and drags me into it. However, I must have recently agreed not to attack the Blue Vodyani when they asked me to halt attacks while we were in Cold War. Now my diplomatic status with the Blue Vodyani is War, but whenever my fleets are on the same system as one of their fleets, I am unable to attack them because of "previous diplomatic agreements".

Here is the contradiction displayed on the Diplomacy Screen itself:

Here is the autosave of the turn where this issue starts:

AutoSave 9274.sav

At the beginning of this turn I'm not at war with the Vodyani, but it soon automatically pops up saying my alliance has been dragged into a war. This issue persists as I continue on to future turns.

These AI alliances really do seem to cause trouble...

Version

Current, 1.5.11