How to add custom ringtones to iPhone 8 using iTunes?

I've already found that article and it does not work. Copying and pasting into the "tones" folder on my phone under iTunes does not work, and what's more the "tones" folder doesn't even show the tones that are on the phone.s not work, and what's more the "tones" folder doesn't even show the tones that are on the phone.

Ok, so I've had some time to work on this again. I tried deleting the hidden tones on the phone using ifunbox as Apple recommended. I still cannot add my ringtones, so now not only do I not have my new custom ringtone, I also don't have the custom tones I've had for years anymore. This is starting to get very annoying!

I gave up on iTunes and on trying to get any help from Apple, and decided to "side load" the ring tones into the phone using iFunbox. Rather than simply using iFunbox to delete the tones as Apple recommends, I used it to "import" the tones into the phone and it worked. Still don't show up in iTunes, but I don't care - they're on the phone and that's what counts.

I'm quite disappointed that in order to perform what should be a simple and intuitive task has been made into a hair-pulling exercise in futility by Apple and that I was forced to use third-party software because Apple's own software doesn't seem to be capable of doing this simple thing.