Indirect lightning problems (alright after baking but artifacts appear after a couple of seconds)

Hi guys, I have been experimenting with interior lightning today and all went well so far except one specific issue. I expected some indirect lightning visual artifacts due to the Preview light quality, but when I baked the scene in Production quality I have found some weird artifacts especially in the room corners where it is darker.

The lightning is baked alright (see 1st pic) but after a couple of seconds it changes to a broken state (see 2nd pic), there are 2 instances to showcase my issue. You can also find the World lightning settings.

Hi guys, I still have this issue and can’t find the root cause. Any help is appreciated!