Besides the collision issues I posted about in another topic (which I'd noticed before the updates of the last few weeks), I noticed some oddities with the recent updates.
The last build I was using consistently enough to test combat was v41, and I didn't see these issues there, so it seems like one of the updates since that might have introduced them. In any case, the first bug is that PCs that don't have the double attack trait can occasionally attack or act twice in the same round. I'm not sure why and have been unable to reproduce it consistently, though it does seem to become *more* consistent when the other bug comes into play. This second bug is simply that some enemy attackers hang back and don't attack at all.
I'm going to remove the creatures from the combat I've been using, repopulate it, and see if anything changes. Though as I said I'm not able to get the double acting consistently, I'm usually able to get it at least once a battle.