iTunes Match won't update on iPhone
Coincidence or not, since I installed iOS 11.3, iTunes Match won't automatically update on my iPhone 8 when I add new music to my iCloud music library via iTunes. The only thing that works is turning off iCloud Music Library in Settings and turning it back on every time -- which is tedious and results in the deletion of most of the music I'd downloaded to the phone.
I've tried quitting all apps and restarting the phone, which doesn't make any difference.
I'd be grateful for any help -- thanks!
iPhone 8, iOS 11.3