In my time 100% Heartfire, did I run into 4 bugs of which only 3 is major/game breaking.

1. Do not assign any follower your travel with as Steward, since this can cause them to disappear forever, when Dismiss (Even if you drop them off in front of the assign house)
2. Do not assign a follower to 2 houses as Steward, since it will cause them to stuck in last house AKA no way to get them out of the house, even when told to follow you.
3. Make a save before working on the wings, since you change from Library to Kitchen/Armoury after building 1 item (Door example) will cause the wing not to count and effectively lock you out of Master Architect Trophy.
4. A Dead dragon will fall infront of Lakeview Manor after Small house is build and will never disappear.