I faced this problem few times, when I baked light last week it was ok, but when I rebake scene on next day light stoped bouncing (like it I set it to 1), yesterday bouncing came back (when I decrease bouncing from 50 to 10) and today I didn’t change anything, just added on mesh, and bouncing disappeared again. What’s wrong?
Never really faced any thing like that, really strange behavior.
You might want to try create a new empty level and go step by step and see if it is possible to recreate the issue (Or may be try a new empty project)
Ok, I created new level, put the house mesh and set bouncing to 50 and got dark lightmap. Same in new project. Now it seems like the bug was bright lightmap, not dark