When launching VM hosted apps, the Windows logon screen might appear before the app is fully launched.
To change the duration of the grace period, set the following registry key: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Citrix\wfshell\TWI Name: LogonUIHideTimeout Type: DWORD Value: Any value greater than zero in milliseconds (for example, 20000 milliseconds for 20 seconds 

Problem Cause

There is a grace period of 15 seconds after which screen appears this is expected behavior unless you make the reg key shared in this article 
Note: During the grace period, there is no obvious indication to users that the app is launching. Configuring too high a grace period can delay application launches and cause users to inadvertently launch apps multiple times.