Sims Family Completely Disappearing?

So everytime i try to go into CAS or split my household they completely disappear. I mean completely disappear, the only place they remain is in my library. They disappear off their world & all the people they have relationships with, they don’t show up. I’ve been able to manage going back to a past save and it’ll load up but the most recent save just won’t load my family. Is this a sim glitch with the update? or could this be a mod?