I went thought many problems with Metadata mistagged or missing causing problems with my library. This was a long time before Roon was even a glimmer.
Then when I purchased Roon in August 2018 I still had to fix/ edit some of my library and still do every once in awhile. The most common problem was album splitting not for the stuff I had ripped with CD-Ripper but from other sources very frustrating. Album covers too.
Google DBPoweramp look at PerfectTunes.
It can be helpful if Roon is incorrectly splitting songs of a specific Album into two listings. This is often caused by incorrect metadata data embedded in tracks. Specifically things like Album name, Artist name, date, even incorrect track numbers. Any tag that should be same across all tracks not being same. Could be as simple as an extra space. It’s meta data editor which is built into windows explorer (right click menu) also allows you to select all songs of album and edit information that is (or should be) same across all tracks and save. (To get an idea of what Metadata is analyzed by Roon, edit album and look at metadata preferences tab)
Perfect tunes metadata editor can also embed album art in flacs and waves which you can tell Roon to prefer. Example Roon selects wrong album art for all Led Zeppelin digital hires remasters. Once I embedded in flac files it showed correct versions.
Perfect Tunes also analyzes untagged music, to be clear it listens to the song helps identify one or all tracks of an album. then you can choose one of four Meta data sources (Including Discogs) to select and update. When I did most of my collection in 2008 it had trouble with vinyl recordings, they might not be in the database. This also causes problems in Roon as song lengths don’t match what it has. Would imagine it is better now as databases improved, consider sharing your updates to databases. Especially if you had to do manual entry (rare). Unfortunately its interactive as always you have to confirm some of its findings. Mistakes can happen with any automated processes. Some databases also have inconsistencies in them so it ask you to check and confirm. Single apostrophe is very common cause of this. A friend ripped his entire CD collection without meta data this was a god send for him.
Once metadata is fixed scanning with Roon again doesn’t always solve problem move out of directory and move back 5-10 minutes later. Guessing that forces a scan of all metadata entries. (Make sure you do a library cleanup if doing many tracks/albums saves space.)
CD Ripper, ripped well over 1500 cd’s and have never heard a glitch. Make sure you read how to setup and investigate the best optical drives to use for ripping (I use Plextor). Create log files as you go. It uses AccurateRip to compare your result against others rips of same disc, so purchasing a good popular drive can be piece of mind (there are lists in the forums). CD-Ripper lets you pick from 4 meta data sources including DISCOGS, GD3, Music Brainz and freedb.
PS A bad rip can cause very loud distortions potentially speaker damaging. Also cause missing nuisances in music.
I can highly recommend Lossless Flac many articles on this by people much more knowledgeable than I. Not default you have to change.
If your stereo costs more than my car go wav, you can also afford the space for your music 
Audio converter also comes in handy with Roon when it thinks a file is corrupt. Just reconvert to same format. Maybe a better term is incompatible. Corrupt would be poor sound to me but really apples and oranges its still a fruit in that Roon not able to play or then even show it.
There is an excellent forum for how to use always check stickies before asking questions. Spooner (his nickname) is very responsive.
Yes it’s paid and on paying for updates if your boss asks you to update work you did two years ago do you come in for free to fix it?
Some music I used Shazam. There are several similar programs now for phones etc. they analyze music and provide results rare now a days that it doesn’t recognize some music.
Have 2350 albums flac, wav, dsd might be 100 albums of mp3 left to replace as I buy or find. So have a bit of experience with this.
Make sure you keep at least two copies of your library. I have three the third is offsite. It took decades to gather/create my library. No I won’t share it, Artists have to eat too.
For backup consider Allway Sync only adding updated files to your backup again some review might be required. If interest could do a separate write up on it website is good.