Hard-wire sync iTunes on MacBook to iPhone stuck on step 4 of 4 "Waiting for changes to be applied"

I sync the music on my MacBook iTunes library (selected playlists/artists only) to my iPhone via hard wire and the Finder. It used to be that you had to open Activity Monitor and kill MDCrashReport, but that "activity" isn't showing up anymore. It is not syncing my changes and gets stuck on step 4, "waiting for changes to be applied." I have tried restarting everything and several different orders of connecting, disconnecting, ejecting, etc. I have the phone in airplane mode and all apps killed. All iOS and MacOS are up to date. I can't think of anything else to try. Is anyone else having this same problem?