Issue
The save game starts to disintegrate itself. Lots start to get deleted, causing endless loading, loading into empty lots.
This happens to save games that have lots of R-rental units in all ...
Ideas
I've had this issue in a save with many rentals, but not an extreme number (around 50 units I think). At a certain point, loading any lot, I had the wrong lots showing (the default ones instead of the ones I built).