I just want to add that I'm also having this problem on one specific save, I've been able to enter the other lots in build mode in Ciudad Enamorada with no problems, but now when I enter the 2 speficic lots in Vista Hermosa, namely Caminito Del Deseo and Casita Del Amor it's just an endless loading screen, I left it for a good 10 or 20 minutes and eventually had to force close the game because I didn't think they would ever load and it should not take that long, I was able to enter the other 3 lots without problems, Laguna Del Abrazo (The lounge), Mansion De La Pasion and Calle De La Promesa, all other lots in other neighbourhoods and other worlds are fine as well, I restarted the game numerous times, deleted the localthumbcache, verified the files in Steam and it's still happening, all mods are up to date as well.
I don't have any last exceptions generated and when I force one through better exceptions it doesn't tell me anything is wrong.
All the lots load fine without any problems in other save games so it's just happening in this save game which is bizarre, I certainly don't want to loose this save file as @stasj912 mentioned in their post it's a big save I spent alot of time making, live mode works ok and can travel do stuff in all other lots without issues, I haven't tried travelling to these 2 problem lots yet, I have a feeling they will just get stuck in an endless loading screen. ☹️
Edit ; I just tried travelling to Caminita Del Deseo in live mode with a sim and it's just an endless loading screen again ☹️