Can't get iTunes wifi sync to work

I have an iPhone 6 and a MacBook Pro (2017 model with touch bar). I am trying to get iTunes wifi sync to work since It's annoying to plug my iPhone into my laptop with the adapter. I have both devices connected to the same wifi network. In iTunes, I have checked off the "Sync with this phone over Wifi" button and pressed apply. I have tried resetting both devices multiple times, turning wifi on and off again, and turning both devices off and on again. I've even tried going to Activity Monitor and quitting the "AppleMobileDeviceHelper" process, reopening iTunes, and resetting both devices again.

In the iPhone settings General > iTunes Wifi Sync screen it says "To enable Wi-Fi syncing with iTunes, connect to iTunes on your computer using a cable and click "Sync with this iPhone over Wi-Fi". But I have already done this as described above. The button on iTunes is clicked. I've applied changes, turned them on and off again, etc. As soon as I unplug my iPhone from my laptop, iTunes no longer recognizes my iPhone and the iTunes Wi-Fi sync screen still says "connect to iTunes". My Mac is running macOS Sierra 10.12.6 and my iPhone is running iOS 11.2.6. This is extremely frustrating. Any help would be much appreciated!