Album on Apple Music library not seen on Iphone under Music?

I have used iTunes over the years to build up a library of music albums. Some I have purchased via iTunes. However I had CDs from previous days and I RIPd these and added them to the library with no problems (Even tied up the TAGs and Art Work where needed). This was on my Windows PC formally Win 10 now Win 11. I have always been and Android Smart phone user. No problems there with my library. (Mostly changed the albums to MP3 format put them on my SDcard on phone use any Music Player. Easy. I have just purchased a second hand iPhone 8 and feel that Apple should be even better than Android for music. So I have put Apple Music and iDrive etc. from MS store on my Win 11 PC. Set up phone to Sync etc... Most of my albums appear on my iPhone and I can play them. But some albums don't appear. So I took one of these albums as a test. I deleted it from the Apple Music Library and re-added it - didn't work. I restarted the iPhone. I have checked that the phone is synchronisinig with the PC. I plug it in via USB so no connection problem there. Not sure what else to do. I am new to Apple which I am not a great fan of compared to Android. But decided to learn Apple. I am a member of U3A the IT group. Most of them Apple. Feel as ex IT person Windows UNIX networking I might be able to help them with any Apple problems. Looks like I won't be much help to other users of Apple. Greatful for any help or advice.