Sims will suddenly go 'Out of the World' to infinity

I have experienced this issue with two separate saves, my bugged save and my new save file. I play with mods, but I don't think this is a mod issue because it's been happening for months. I find that sometimes pressing shift+click and resetting the objects they're using might bring them back to "earth". Other Sims that interact with that Sim also freeze on the screen, and tasks tend to pile up infinitely. Reloading the screen (i.e., entering and exiting CAS, going to a different lot, etc.) works, but it only works for a Sim that isn't frozen or lost in infinity.