Consider the following scenario:
When an application runs, it can display multiple windows when launch different functions.
In an ICA session, the application window shows white screen when user launches the application as it hangs at the server end.
For Example, if the User launches a 3rd party app to take a data backup, it launches the command window and then app freezes till the backup completes. At this time a white screen is seen.

It is an by design behavior,  this issue can be workaround by using the SHIFT+F2 key to switch to Windows Mode.

Problem Cause

In the Published Application that user launches in RDP the window shows the same behavior as in our Published Application. Setting the window at the forefront sends the same event to the window as does a single click. Once a window of a Published Application gets launched, it would be the topmost window on the desktop. This mechanism is to explicitly notify the user that the application launch has completed.