This usually means there are issues with your metadata or something else that means Roon may have found the correct album but isn’t confident enough to auto identify the album, however when you do Edit:Identify Album Roon is giving you potential matches and you are explicitly giving Roon the go ahead to match to that album.
I have written a couple of articles that might be helpful to you, this one explains what can prevent Roon identifying an album and this one shows how you can quickly check for issues with your metadata