@crinrict Okay,
I was able to load in without the EP but the game turned my apartments into generic lots although each had a family living in it and an option to sell the business/retail lot (as if it still was a residential rental), but the lots were in a City Living type of shell when I entered build mode, where I couldn't delete walls or doors if I weren't building in the inside of my property (what I had designated as RR Unit). So I tried to place down another lot but it gave an error, so I tried to bulldoze but it took forever so I quit (I'd consider unplayable at that point)
But lastly I added For Rent back in and was able to fix the residential rentals by turning then from generic lots to RR, although it gave me another infinite loading screen, I reverted then from generic to RR and bulldozed them, only then I was able to make it generic and it finally would work.
It took so much effort but it actually turned out okay, no infinite loading screens on sight. Being honest, for most people I would literally recommend deleting FR and backing up the families to start in a new fresh save file through the Library.
Alright, sorry for the long text, I'm very grateful to you!