Can't Make New Save Files

For some inexplicable reason, my game won't let me start new save files. I open my game, click new game, create my sim, play for a while (saving multiple times throughout), then save and exit the game. But next time I start up Sims 4, my new save file is nowhere to be found. I can still play and save progress in old save files, but all the townies are dead, and I just want to start a new world. I am actually getting really frustrated. This is a game-breaking bug, and I'm so tired of playing for hours in a new world just for all my progress to be lost.

I have tried repairing the game through the EA app, clearing my cache, restarting my computer, etc. but nothing has helped. 

The last time I was able to make a new save file was right before the "blast from the past" event, but I first noticed the bug after Businesses & Hobbies came out.

No mods, playing on Mac through EA app

PLEASE HELP