Played till the end of the Fort Joy for now, found new issues:

1) The second player plays as Lohse and mostly use bows. Most of the time during battles, her bow looks in the opposite direction from where she points it. So basically, bow shoot backward. This looks very weird, though is a purely visual bug.

2) Something wrong with Throwing Knife skill for Scoundrel. It deals tons of damage when used by player character - on level 6 for dual wielder it can do about 130 damage without backstabbing, and 300+ with backstab. When level 8 NPC uses the same skill, it's usually about 40-60 damage.

3) Arena in Fort Joy still doesn't work. They gave me a chance to fight with the second player again, but again after we got teleported to the arena, in a moment we were teleported back and all the dialogs show that we lost. For both of us.

4) I've found that I can cure pigs from Necrofire by using Blessing skill. But the NPC in a maze called something like Hystorian can't be cured from the same Necrofire curse.

5) After we've left Fort Joy and ended up on the ship, we've immediately seen that there is a big lag when you're trying to loot any container (including corpses). Like it takes some time for a character to open anything. It feels the same issue as I've encountered on Divinity: OS 1, after going to the 3rd location, and visiting the 2nd again, however that time lag was added for any click on the map. Now it's only for looting the containers.