Hey CtrlAltMusic!
This appears to be an example of the issue explained in another recent thread. Basically, Spotify has done some sort of update that has caused even official (non community) implementations of their Spotify Connect functionality to break or be very unpredictable on a per-account basis
We’re currently testing an upgrade to our spotify provider, go-librespot, just in case that helps but we’ve only just updated our office unit with that this morning and have a lot of testing to due given how inconsistent the issues were on a per-account basis previously