After upgrading to Windows 10 creators update (1703) in an existing environment with Citrix UPM in use the start menu stops working and Search/Cortana is disabled.
The following message can be seen if clicking the start menu multiple times
Update to Citrix UPM 5.8 (released as part of 7.14 on 25/05/17) resolves the issue as described above. Please ensure if using Windows 10 1703 that UPM is upgraded/using version 5.8 and ta da!!! Now working again
Citrix Proile Managment 5.8 also available here seperate to the 7.14 ISO.