I can also confirm this issue. I have tried:
1: Reloading a save prior to the quest and proceeding as normal
2: Building both plots
3: Building both plots prior to talking to Pandora at the start of the quest (but after the quest has begun)
4: Building both plots prior to the quest starting
5: Deactivating pandora and reactivating her via the console
6: Killing pandora via the console
I ended up just using the console to push the quest forward. For those unfamiliar with the process, like I was, just open the console and search "help roomforimprovement 0" and it'll generate all the references to the quest. Locate the quest's ID, located next to the entry listed as "QUEST: kgConq_mmc18_roomforimprovement" and note the ID listed in parenthesis. Then just adjust the stage via entering "setstage [ID] [desired stage]". So for me it was "setstage 0e008d2f 20" that ended up doing the job. I believe quest stages are usually in intervals of 5, so that may help when you don't know the desired stage (like I didn't).
Props to the team for getting the quests to work as well as they do in such a chaotic environment! I cannot express how much life your hard work has breathed into this game.