act II
i'll send a save along to larian, but thought i'd pass along exactly the sequence that (seems to) start the horrid slowdown (running through honey) and eventual monsters that don't attack - at least this was it for me.

after completing the larger mushroom forest i returned to finish the last couple quests i had (before finishing with alchemist).
i stopped at the imp ghost and told him of the sister.
i then went to confront her.
after leaving tent, there is no 'illumination' around character's position (NOT fog of war, just the light). you'll then have difficulty getting into other tents and, eventually, attempting to enter BF6 the monsters no longer attack.
to alleviate this, just DON'T talk to the sisters after the ghost's disappearance.