The below is the fix from PSF if you could kindly direct them too first - Amber Britton (#350577)
'Does this user receive the Windows popup when they log on to the Cloud that lists all the tickboxes (for printing, any resources they want to access within the Cloud)?
One of the options is 'Clipboard' and, if this isn't ticked, the user will be unable to copy and paste within the RDP. A manual method of checking access as well is to double-click their RDP shortcut > when the login screen appears click 'Show Options' in the bottom-left of the window > Local Resources tab > check if 'Clipboard' is ticked.'