Some of the album that I added to my library and that come from Qobuz cannot be played (marked “unavailable” in red), but still exist in the Qobuz database. And when I try to remove them to add them again, they would not remove!
The workaround for this (kind of) issue, is to Edit the Album and to re-identify it . It does not matter to identify it to the correct album (as you are going to remove it anyway).
when one identifies an album, and save it, Roon will write in the corresponding record in its database. That is enough for being ‘available’ for removal.
Not a great solution if your collection has hundreds of albums that have been removed as was my case. They need to sort this mess out rather than having to use workarounds.