Ever since 1.6 (or a beta of it, I'm not sure when exactly this started) I've seen some weird things happening with my last game. Twice is this game I've had another civ invade my planet (once it was actually successful) while not at war with me, nor the war declaration being brought up afterwards. This is my first game since 1.6 went live so that's why I think it was it, not a beta. Then again as the details below will show, it isn't very easy for me to replicate the problem as it was initiated by the AI.

I was playing a custom race and the two offending races were the Thalans and the Yor (don't think that has relevance, but mine as well include it). There were the two UP rules in effect involving war: 1 week heads up on war declaration before hostilities and the neutral ground rule. Side note on the 1 week no hostilities & the AI...they seem to not take this into consideration and attempt to fight that week (just as they do to trade ships with the UP rule of a trade federation /shrug).

All of a sudden on their turn I'd see the invasion window pop up, hit the button and then when I get back I started to "scramble the jets" to retaliate...but no war declaration showed up and no further invasions really happened afterward. The second time I was actually prepping for a massive attack on the rest of the galaxy (everyone else was allied) when it happened, so I just took that as my moral "reason" to fire across the bow of the other 60% of the galaxy.

I think both planets were created by the mega event in which some civ activates a precursor artifact and all planets w/in 2 sectors get a 4 PQ bonus. I had custody of these planets for many many months prior to invasion.

If I think of any other situational details, I'll reply here.