Yeah, sorry, I'm not having any success recreating it. If anything like it happens again, could you give a screenshot of what it looks like when it freezes?
As far as saving goes, you can manually save at any time by quitting to the menu - it'll place you back in the exact room you were in when you reload. I know it's a bit hacky to have to do that regularly, but doing it after major milestones should prevent any progress loss. I'll def make sure to fix upgrades not autosaving the game once the ratings period is over.