Dictation doesn't work with external monitor (M1 MacBook Pro, Ventura 13.2)

I depend on the dictation feature in Mac OSX. With my external monitor (Dell P2723QE connected via USB-C), I close the laptop to work with the big screen. Wireless external mouse and keyboard work fine, and dictation sometimes (not dependably) works for a spell after a reboot. But after putting the Mac into Sleep mode or closing the laptop when working with the external monitor, it no longer works.

I've tried it in different apps (Chrome writing emails, Word, all kinds of programs...). I've used OnyX to clean up the Mac (I mean, it's only a few months old, but who knows). I've tried external mics. I've tried opening the laptop while working with the external monitor. Nothing works dependably. Except when I don't work with an external monitor--working without an external monitor on the laptop alone is mostly fine.

I see some threads where people have had similar issues, but I have yet to see any resolution. Any ideas, compañeros?