Sims unable to use toilet, shower, woohoo. Starts the action and then immediately glitches and they stop. Doesn’t fill their needs
Ideas
This is happening with me too, I'm also on a Mac. At first I thought it was just my infant sim, but so I aged her up to a toddler. Kept happening. I moved the two sims out that I really want to play, and it's happening with them, too. They won't finish any of their actions. A new save file seems to complete it, but this is one I've been working really hard on.
Yes, I use mods, none of them out of date though. Would CC do it? Like clothes, shoes, furniture? I only have one mod installed, and I'm not seeing any other users of the mod having difficulties.
Please move your mods folder to the desktop, delete Documents > Electronic Arts > The Sims 4 > localthumbcache, repair your game and then try again on a backup of your save to see of you can duplicate the issue on a game with no mods.
Any issues reported in the bug forum must be tested on a vanilla game.