ShowInstallationWelcome -CloseApps - CloseAppCountdown ignored

Hi there,
I have a few packages where I use the -CloseappCountdown and for some new packages this won’t work anymore…

Here’s my Setup:

Powershell =
##* PRE-INSTALLATION
[string]$installPhase = ‘Pre-Installation’
Show-InstallationWelcome -CloseApps ‘exefile1,exefile2’ -CloseAppsCountdown 600

Logfile =
[Pre-Installation] :: Check for running application(s) [exefile1,exefile2]…
[Pre-Installation] :: The following processes are running: [exefile1,exefile2].
[Pre-Installation] :: Resolve process descriptions…
[Pre-Installation] :: Finished checking running application(s).
[Pre-Installation] :: Force close application(s) [exefile1,exefile2] without prompting user.

Application in SCCM2012R2 =
User notification set to “Display in Software Center and Show all notifications”
Deployment Type User Experience set to:
Install behavior: Install for System
Logon requirement: Whether or not a user ins logged on
Installtion program visibility: Normal

Or will it only with with “Only when a user is logged on” ?
Why does the script simply kill the proccesses instead of asking the user to Close the apps with a Countdown of 600 seconds?

I am using Script 3.6.8

Thank you.
Regards, Manuel