How to make my Bluetooth headphones be recognized as an output device?

Hey there,

I have Sony WH-CH700s and this problem just now started. When my laptop is connected by HDMI to another monitor, my headphones sort of flicker in and out of recognition as a sound output device. That is, they play sound for a split second but then aren't recognized anymore. The whole time, they are connected to Bluetooth, it's just sound won't play through them.

I've already tried disabling both the monitor's audio and the laptop's speakers, and nothing.

This isn't a super urgent problem, but I just wanted to see some ideas.

Thanks in advance.

:)