iTunes iPhone Album Art wrong

Been a very happy iPhone owner since the 4. Got a 12 pro max last year. It's been a perfect phone for me too. BUT, the last 5 or so attempts of adding music albums to my phone via my PC, it usually end with the wrong Album art 50% of the time.

I don't allow iTunes to manage my albums. I have 20 plus years of uploading/ripping music into digital, plus purchases. Over 64, 000 song files on my music drives, so only a fraction of my music makes it on my phone. I also run several other music apps & programs & have long since adhered to a <Artist/album/Year> format. I also subbed my music into Genres per drive. Needless to say, I keep my music on my PC drives my way. Only some gets added via folder to iTunes. Then hand picked albums are added to iPhone.

It's worked very well till this last year. I've added albums via drag n' drop in iTunes when phone connected via cable. I followed a couple of suggestion to fix: like checking to art within the phone folder via iTunes & it always looks proper & correct. Even found a few where the art isn't showing. Did a repair & moved on. When I disconnect, its remains messed up on 10 - 20 albums. I've even tried deleting from phone, reboot, re-drop albums to phone....no luck.

Surely I'm missing something?? I'm quite hardnosed when it comes to the sorting & cataloguing; this has me wanting to put a nail through the phone, or just delete the iTunes app entirely. But what else can replace the music app on iPhone. (( Wish there was Win Amp still ))