Hi @sparafucile.
Thanks for reaching out and for your detailed post.
I appreciate the troubleshooting steps that you did to try and fix it, let me help and figure this out.
Generally, each music service's UI (User Interface) within the Sonos app is designed and implemented by the service themselves using the Sonos provided API (Application Programming Interface).
Have you seen your playlist within the Sonos app in the past?
Are you seeing your playlist in the native Tidal app?
Is it happening even using different controllers for the Sonos app?
I suggest doing a refresh on your network by rebooting your router and Sonos devices by unplugging from power.
Then, plug in the router first, wait for it to boot up, and establish the connection before plugging back in Sonos products one at a time.
When everything is re-booted and you are connected back to the Sonos app please let us know the results.
I'd like to check also some data from your system. Please send in a diagnostic report through the Sonos app and reply with the confirmation number. I'd start by reviewing your system and see if there’s anything possibly causing this issue.
Let us know how it goes and if you have any questions feel free to reach out, we’re always here to help.