iTunes won't let me sync ringtones

I'm currently attempting to upload a custom ringtone to my phone. The phone is a 5s and is currently on iOS 11.4. I am using iTunes 12.8.0.150 on Windows 7.

I looked up a few guides online on how to upload custom ringtones and followed the steps, and after I converted the ringtone to an m4r file, I attempted to copy and paste it into the tones folder under my iPhone in devices. Instead of showing up normally, the file's name is in grey and has a dotted circle next to it. I spent about 10 minutes looking at guides on how to fix this, and tried everything they recommended. I made sure "manually manage music and videos" was selected under the phone's "summary" tab. I made sure my phone had space for the file (I currently have 9 GB free). I've followed every last guide I can find and nothing is working. Can anybody help me with this?