iCloud Desktop & Documents not working

When I go to system preferences/icloud/icloud Drive/options and select 'Desktop & Documents folders' I get a brief 'setting up' message but nothing else happens (no folders apper in iCloud Drive). If I click 'done' and then re-click iCloud Drive/Options, the 'Desktop & Documents folders' in UNCHECKED...


Any thoughts on how to get this to work???