Spotify cannot connect to Chromecast

Running iodé on FP5. Trying to stream music from Spotify to my speakers via Chromecast, but it fails to connect.

I’ve had similar experiences before that have been VPN related, but I have the correct VPN settings to allow local network sharing.

Tried disabling blockers for Spotify in the iodé app, but that didn’t fix it.

Any ideas on what could be causing this?

PS. Yes I will eventually switch to a Chromecast alternative. Right now I’m looking for a better understanding of iodé and where the connection might fail.