Same issue. Having problem with my iPad even syncing.
Pardon me if this is way too simplistic, but this works for me and gives a (very small) indication that Syncing is actually happening.
Open Music (RIP iTunes). Select the device you want to sync on the list of devices on the left. Click Sync Settings at the top of Music (again RIP iTunes), a Finder window should open and the device to be synced will be listed at the top of the Finder wiindow and listed under Locations on the left. Select Sync at the bottom right of Finder. There should now be a circle at the device listing in Locations which will "fill" as the device syncs. That circle will fill and clear as each part of the sync is performed. This is a REALLY LOUSY way to display the sync prrocess but apparently we're stuck with it for now.