I applied the DLC patch on the day it came out and started playing co-op with a friend on a pre-patch save. Now I've been noticing a lot of glitches appearing. I'll list all the new glitches I've seen:

Combat log is missing.
Sounds missing from abilities at times.
Status Icons not updating properly (i.e., the game will show 3 turns on a haste status when there's actually one).
Stats completely resetting on a character when loading.

The first and last are the most annoying and game breaking, while the middle two are just jarring. Does anyone know a fix?

The combat log issue is fixed in the 1.0.177 update, which should probably arrive for the GOG version Monday.

Missing sounds with abilities have been reported (for the Expert Marksman stances), which I assume are due to some sound effects being added or changed. IIRC there have also been reports of some statuses not updating properly in some circumstances.

Stats (etc) being reset when joining a co-op game or loading is a known issue (since before the recent patch) that has been difficult to reliably reproduce (though some people have this occur often). Usually reloading will get it working properly.

Thanks for replying. If that's the case, then this new patch just exacerbated the issue for me, as I never experienced this problem before. I can honestly tolerate the more jarring issues, and if the combat log problem is fixed then my playthrough can proceed more smoothly. What I'm ultimately paranoid about is that my updating the game with new features in the middle of a playthrough (I'm in Luculla Mines atm) contributed to breaking it, and that the only true solution for most of these issues is to begin a new game. I'm currently downloading the game again to reinstall it to its pre-patch condition. However, while I suspect it won't be the panacea I'm looking for as the most recent save contains post-patch progression, I want to eliminate all potential solutions that don't involve starting a new game.