Alright, I think I found the issue - it's part of the autonomous sleep coding. You can get around it either by disabling Visible Brainpower or sending your sim to sleep manually.
Unfortunately the bit of code that's acting up is load-bearing, so I'm going to need time to poke at it. I should be able to roll out a fix this weekend, alongside some other minor bug fixes.
Edit: okay, update is live.