[FR] Can't Go to Manage Worlds After Changing Lot to Residential Rental

I've waited for over an hour to save my game while in build mode. Once finished, I hit the Manage Worlds button:

1. Downloaded lot from gallery. It was set to Residential and I changed to Residential Rental.
2. Designated apartments.
3. Placed apartment mailbox, fuse box and water heater objects.
4. Double checked lot/apartment info; made sure all necessary objects are placed i.e. toilet/shower etc.
5. Tried to save game; this took 1 hour 5 minutes.

So far it's been 16 minutes and it's still loading.

EDIT: More info.

1. Force quit game.
2. Cleared caches and deleted scratch folder inside Saves folder.
3. Loaded the save that took ages to save.
4. Clicked on lot that is now correctly set as a Residential Rental but now, there is a big red X where it should show what the inside of the apartments look like.

This is actually my second attempt at placing a lot from the Gallery, changing to Residential Rental and this bug appears. I have already repaired my game and did a "folder refresh".

Edit By Crinrict: Adjusted tag to fit naming conventions.