We’re here to help and I’d be happy to troubleshoot this issue with you.
Can you please let me know where exactly you’re seeing the music as unavailable? Have you tried rebooting your Nucleus as the first troubleshooting step here?
You can do so by using the physical button on the Nucleus itself or by navigating to the WebUI and then pressing reboot:
Can you please let me know if rebooting has helped? Does this behavior occur with both TIDAL and local library media or just one and not the other? Can you please post a screenshot of your Roon Settings -> Storage Tab? It should look something like this: