Published RPD Desktop was not copying and pasting, yet a direct RDP to the same server worked.
The citrix session sharing was not working for the published application. The citrix server was launching a fresh session on another server (ICA Desktop > Ica Server > RDP > Desktop)
No wonder the Cut and Paste was confused / broken.
The published application was edited to REMOVE the tick in Access Control tab for the published app “Allow Connection made through Access Gateway”
Session sharing then worked (i.e the executable just opened directly on the current users desktop) and cut and paste worked as expected.