You’re not alone. This happens with many classical albums and it must be caused by insufficient metadata Roon is supplied with. If it is a local album, I think you can tag the files to resolve this- But with albums from streaming providers I have found no way to force the correct composition grouping of tracks. A way to group tracks and assign them to a known or new composition would be greatly appreciated.
If these are local albums (i.e. not streamed from Qobuz or Tidal, but held in local storage), then you can use the WORK and PART tags to group tracks into compositions. See:
Before you start wielding the metadata tag editor, first check whether Roon has been able to identify your album. Even when an album shows as unidentified, it’s worth using the Album Editor to try and identify it manually…