Sims freeze, won’t do queued actions

Randomly, one household member will freeze and not complete the actions in the queue. Previously, this has happened when there was only one action queued, and adding another action seemed to prompt the sims to start doing the first one. But now, no matter what i tell the sim to do, the queue just fills up endlessly, and the sim is frozen. 

This also happens when I am controlling another sim in the household, and the first sim autonomously tries to fix their needs, but freezes. For example, the sim had a very low energy need, and also a low bladder need. When I switched control back to her I saw that she had autonomously queued about 5 different actions to try and fix her needs, but was just frozen and not doing anything. Then her moodlet changed from uncomfortable to asleep, even though she was just stood doing nothing?! And I don’t think her needs were fixed at all, but I can’t remember exactly.

I haven’t got any screenshots of this, but basically it’s just a really long queue and the sims just stands there.