Why won't Bixby or Google Assistant work while I record?

I'm on Samsung Galaxy S24 Ultra. If I have a recording active, then I find that Bixby and Google Assistant refuse to enable listening in the background to wake up, by calling them up using voice.

Google Assistant can't start when another app is using the microphone

I can start them manually, so the problem is not exclusive access to the microphone. I've tried like five different recording apps and I just get the same message, when I try to activate it in settings. I'm not really sure what the problem is here.