Yes! I removed all the hidden tones. When this started happening (it was when I was restoring my new XS Max from my previous backup) all the ringtones I had were hidden (None showed in the library but they were all there in the phone). I used FunBox as you suggested, removed all the m4r files with random letters, and the plist as well. I did keep the sync folder inside the ringtones folder. I didn't delete that, but you didn't mention to so I left it. As for valid m4r files, yes, most are dated 2013. I've been using the same custom ringtones since then. I'm pretty adept at iPhones. I get a new one EACH year. Last year with the X there were no ringtone issues. This is the first time ever. Like I said, there are 3 of my 8 or so ringtones that will sometimes sync and others not. The remaining 5 are always grayed out with the dots. They never want to sync at all.
This is why I am so confused! I've totally followed what you stated down a tee. I've rebooted when you said to. I don't know what else. My other issue is I don't want to delete and start from scratch. If you can think of ANYTHING I might have missed or forgot, please tell me. But again, I've tried everything you stated. I copied and pasted, I dragged and dropped. Nothing. I did even remake one of the ringtones yesterday just to see if in fact my old ones didn't work properly. But that too failed.