'File Types can not be imported within a workspace control session' message is shown when importing filetypes using the Ivanti Workspace Control Console.
End-User is running a Workspace Control Session
Make sure the Ivanti Workspace Control Console is not started in a session where Ivanti Workspace Control is active.
For workstations or laptops make sure the Agent is set to manual (Administration > Agents > Rightclick Agent > Run Workspace Composer > manual)
For Microsoft Remote Desktop sessions or Citrix Published Desktop sessions, make sure the end-user is excluded from the Custom User Interface Policy as described in the Help File.