So going back and playing it a bit more, I think I understand the card game a little better? I managed to get a group of 4 people total, though one randomly ran off on me in the middle of the night =/. I still think it could do something with all the cards that a player may be forced to discard, like replenish some of that blue energy bar or something. Not sure, but it would make it so they aren't just taking up space. But otherwise, I think I know what my actual strategies are in the game.
As for the combat bug, I think it was actually the same bug that people have been mentioning where the ability to hit anything disappears after a day. That said, I have found a few other quirks of the bug that I don't think have been mentioned yet, so hopefully they might be helpful to know? First, while you can't damage anything, you can still, technically, interact with them. I learned this when I swung at a tree, was unable to hit it, but my allies knew to assist me in chopping it down anyways. Second, you can still hit structures you have built, and the purple statue. For some reason, those have been unaffected by the bug. I don't know if that will help you with trouble shooting, or if you've already figured it out, help prevent new bugs in the future by knowing what else is or isn't being affected.