I got a new iPhone 15 Pro right after Christmas and couldn't get my computer to recognize it. But today when I saw on another forum that it might be the cord, I bought one (USB-C to USB-A) specifically for transferring files and now, my phone is syncing to iTunes. I spent several hours on the phone with Apple Support last week and even asked if it might be the cord. I told them that my laptop didn't have a USB-C port and I was having to use a different cord and was told that wouldn't be the problem. So if you have tried everything else, uninstalling, reinstalling, restarting, updating, and you still don't have an answer, try the cord.
I was also told by Apple Support that they will soon be doing away with the music portion of iTunes altogether and will have Apple Music and Apple Devices for music. ITunes will be solely for podcasts and books. He didn't say when that would occur. But if you download Apple Devices while still trying to use your iTunes, it will disable iTunes.