HomePod mini sound loss

Hello,

I am currently using a HomePod mini as the speaker for my Mac. Which works fine after booting up the mac.

The problem occurs when the Mac is then locked and unlocked again. The source reverts to a different (default) source and upon selecting the Mini again, no sound comes through. Meaning I have to reboot the Mac every time I wish to use the Mini.

If any one knows what could be causing this (bug?) and knows how to solve, I'd appreciate the assistance.

Thank you