iMac late 2009 - OSX El Capitan ; iTunes 12.8.2.3
Had same issue since 4 days ... Called to Apple Support, and after reinstalling OSX El Capitan still same problem... Phoned again to Apple Support with 'senior support member' : problem had nothing to do with my (old) computer nor my OSX ( although problem occurred mostly with El Capitan en older OSX) nor iTunes version but something went wrong in the connection with the Apple Server for Apple Music... he was going to address the problem with the iTunes/Apple Music developers...
This morning the problem was solved at least for me ...
I am again lucky owner of a Mac...