The behavior you are experiencing is likely caused by the size of the playlist. In your diagnostic data, we are seeing a 400 (Bad Request) error coming from Qobuz, which often happens when a request is too large or times out.
We recommend trying the following steps to troubleshoot:
Test with a Small Playlist: Create a new test playlist with just 5–10 tracks and see if it syncs or plays correctly.
Split the Playlist: If the problematic playlist is very large, please try breaking it down into smaller playlists (around 500–700 tracks each).
Refresh Account: Go to Settings → Services and try logging out of Qobuz and logging back in.
Please let us know if any of these steps resolve the issue.
Did consider this, and went the other way: i Exported the playlist from Roon to a Soundiiz-format (CSV), bought a subscription at Soundiiz, imported the playlist and migrated it through their service. it was automatically split into two lists, where the first one was 1999 tracks, the other about 1750.
A complex list to handle, for sure.
Worth noting is the fact that Qobuz limits playlists to 2000 items, obvious when managing these within Qobuz.
Worth adding a limit to Roon for these situations?