These two issues have appeared multiple times so far on playing this in an online co-op mode.
I did a search, and didn't see where they were mentioned, but I do admit that I didn't dig beyond the first several results.
A common bug that has been experienced is where we will advance to the point where suddenly the heroes will not be able to speak to anyone, including each other or their followers.
We were able to recreate this multiple times around the Elf-Orc Blood Feud quest, both with one hero and companion present, and then with both of us present. We were opting for the approach of just killing the elf, and afterwards it could be seen that we had the discussion exclamation point over our heads, yet we were unable to speak to each other, and unable to speak to anyone.
We encountered it a couple other times, although the exact trigger wasn't always obvious. The last time before we stopped happened when we spoke to Arthu in his room. One of us went stealth to steal from a chest, and another picked up the book about the golem commands. Afterwards, one of the companions showed an exclamation mark, yet no one was able to speak to the companion, and after going to another area, we found we were unable to speak to anyone again.
The second item: Odd hero chatter happened twice were after a fight that we were both involved, and both successfully defeated an enemy, one of the heroes would want to speak to the other and go through the "you were absent in the fight" dialog, which was annoying the second time it came up.
Other than the above, we're enjoying it a lot so far and look forward to the games continued improvement.
