[MOD RELATED] Sims disappeared from household/Blue flashing square on map

For context, this only happens with the household I was actively playing which was 2 young adult sims who were going to university but lived in an apartment in San Myshuno. 

What happened was: I would play the game with no issues for a few hours, then I would save before I exited the game (once this started happening I saved multiple times), but when I went back onto the Sims 4 to play the household, it was gone. I'd click on their apartment and it would show the household name but my sims wouldnt show up in the bottom left corner like they normally do, and I couldn't press the play button. And if I hovered over the apartment next door and then went to my household it would show the neighbouring households picture but say the name of my family. I have also tried using manage household and trying to access them that way but all that shows up is a blank box with my families name. 

I even used another sim to see if I could at least visit my sims and all I could see was a blank apartment - the apartment would show up greyed out and my visiting sims couldnt enter or knock on the door but they could knock on the neighbours doors. Even if I tried to teleport the visiting sims into the apartment using cheats, nothing would change. The apartment stayed greyed out. 

At this point I have moved them into a house in Britechester in case this was happening because they were living in an apartment. I haven't tried to save and exit from this yet because I am too scared to lose my progress again. 

I do use mods but nothing too major, mostly just maxis match cas and mc command centre (I have tried removing my mods folder but it didnt seem to change anything) 

I dont want to lose this household forever because its my favourite family, does anyone know how to fix this?