Albums not showing up in iTunes

I ripped all of my CD's to my Music folder in Windows 10. In Windows Explorer, all of the ripped CD's appear in their proper folders under artist and album names.

I then went into iTunes and added the Music folder to my iTunes Library.

Now in iTunes I see some of my albums, but many do not appear in itunes. What can be the problem? Why is iTunes seeing some of my music but not other albums?

I've even gone back into iTunes and just tried to add the folder to my iTunes Library containing a particular album that did not show up. Amazingly, it still does not show in iTunes.

Any suggestions or pointers would be appreciated.

One wouldn't think this should be so hard! Why is iTunes such a mystery?