buchtak

No, it didn't. Like I said, the version is 3.02 (it's marked in the tags of the original post), freshly installed from the latest GOG release. 3.02 fixed some other bugs for me such as two Forwyns inside and outside the keep or random -20 raw damage debuff, but not this one.

Actually, due to some patch failures I recently completely reinstalled the game from GOG 3.02 release along with both DLCs. The main screen says it's v3.02.1008. Maybe the Forwyn's presence has somehow been transfered through broken save from before the update?

The same dialog as before the final fight with Lord Gathbin triggers when talking to Marshal Forwyn. The battle can even be repeated up to the scripted part, although this time without any help. After that, I only end up on an empty battlefield with everyone already dead.

I'm experiencing the same bug. The log just won't get revealed as a hidden chest.