
This is one of those scenario's that is difficult to resolve as a Dynamics 365 BC partner, CSP or Dynamics NAV partner as the root cause is not due to Dynamics 365 BC (or Dynamics NAV) code defect or configuration, but lies somewhere else. It is one of those grey areas. The issue is when you are running the Windows Client in a Remote App window, then the focus might get lost and the focus is on the screen underneath the one you are trying to edit. Here is how you can resolve it:
Disable “Use advanced RemoteFX graphics for RemoteApp” in Local Group Policy on the R(emote) D(esktop) S(erver) Host(s):
Computer Configuration/Administrative Templates/Windows Components/Remote Desktop Services/Remote Desktop Session Host/Remote Session Environment/
Hope it does help to prevent this issue from happening.