I have the same issue. I have a Roon Nucleus and a Quobuz subscription. The ‘Add to Library’ function for Quobuz albums has stopped working recently. All I get is a message informing me that it is taking longer than usual and that Roon will keep trying in the background. But nothing happens. Very frustrating!
I was going to log a ticket here as I was experiencing the the same or similar issue. Then I saw the previous post about restarting the NUC. I did that and it solved the problem. Here are the details of my issue below in case it’s helpful to anyone.
Since June 15 or 16-- around the same time I did the latest Roon update–I have attempted to add albums to my library, but they never show up there. These have been albums both from Qobuz and Tidal. I checked each of those apps to see if the albums were being saved from each streaming service, but they aren’t there either. Oddly, one of the handful of albums I attempted did successfully save (TLC’s Crazy Sexy Cool from Qobuz). I tried logging out of Tidal and Qobuz and then logging back in. This didn’t resolve the issue. I have never experienced this problem in my years of using Roon.
I’m running Roon ROCK on an Intel NUC I3BNH. Same hardware I’ve successfully used for a few years.