For anyone who has a Mac and upgraded an iPhone to iOS12, you may notice that iTunes, even though up to date, may not “see” your iPhone to sync or back up.
This happens for PC people, too, but an update was issued - iTunes 12.9. No update has been issued for Mac. iTunes 12.8 was and is the current version.
For Mac, you have to reinstall iTunes 12.8. You can download iTunes here:
Close iTunes. Then install 12.8 (even if that is your current version) and during the install, a message will pop up saying that an update is required. Let it go through the motions. Once installed and when you relaunch iTunes, you should see your iPhone.
Note that I’m running High Sierra. Several people I know running El Capitan are still having issues.
Also, in the event that anyone here uses Finale v.25 (music notation program) - do NOT upgrade to Mojave. Finale v.25 is not compatible. Finale will be releasing v.26 (free for those who are running v.25) later this year.