iPhone 14 Pro music library not fully syncing

Extreme aggravation putting music on my Iphone 14 Pro running iOS 26.2.1. Found that Itunes no longer held my music, so I opened up Apple Music. All my music was gone. I have over 1000 cds on my computer. I have had to use the "Add Files to Library" function (Using "Add Folder to Library" does NOT work) to add albums one by one to Apple Music.

After doing that, I have then had to use Apple Devices to get the music on to my IPhone. However, even though I check the option to sync the "Entire Music Library", only about a third of the music gets on the IPhone. I have also checked the button to sync "Selected artists, albums, genres and playlists" and selected each artist, but the result is the same.

All of my music was imported onto the computer using ITunes and the AAC setting. I never had this problem before. In checking the file formats, the files getting in are m4a, and ones excluded are also m4a. In fact, in a four cd set of one concert, 3 of the 4 were synced on to the phone while the fourth was not.

I am using the Music app on the Phone to play my music.

Solutions? This is very frustrating, because I use Music in my car all the time.