Update-Icinga: Error while updating "icingapowershell"-service

[tectumopticum]

During the execution of "Update-Icinga -Name service -Confirm;" the following error is written to ps-stdout:
"[...] Failed to stop service "icingapowershell". Error: The term 'Optimize-IcingaForWindowsMemory' is not recognized as the na
me of a cmdlet, function, script file, or operable program. [...]"

Steps to Reproduce (for bugs)

1. open a Admin PS
2. use-icinga
3. define a new local repository: New-IcingaRepository -Name 'Icinga Local Stable' -Path 'C:\Users\Administrator\Desktop';
4. update service: Update-Icinga –Name service -Confirm;
   Complete output:

[Notice]: Downloading "service" from "C:/Users/Administrator/Desktop/icinga-service-v1.2.0.zip"
[Notice]: Installing component "service" into "C:\Program Files\icinga-framework-service\"
[Notice]: Updating Icinga PowerShell Service binary
[Notice]: Service User ".\LocalSystem" for service "icingapowershell" successfully updated
[Notice]: Stopping service "icingapowershell"
[
Error
]:
Failed to stop service "icingapowershell". Error: The term 'Optimize-IcingaForWindowsMemory' is not recognized as the na
me of a cmdlet, function, script file, or operable program. Check the spelling of the name, or if a path was included, v
erify that the path is correct and try again.
[Notice]: Restarting service "icingapowershell"
[
Error
]:
Failed to restart service "icingapowershell". Error: The term 'Optimize-IcingaForWindowsMemory' is not recognized as the
 name of a cmdlet, function, script file, or operable program. Check the spelling of the name, or if a path was included
, verify that the path is correct and try again.
[Notice]: Stopping service "icingapowershell"
[Notice]: Service User "NT Authority\NetworkService" for service "icingapowershell" successfully updated
[Notice]: Installation of component "service" was successful

Your Environment

PS-framework-version: 1.9.1

• PowerShell Version used ($PSVersionTable.PSVersion):

Major  Minor  Build  Revision
-----  -----  -----  --------
5      1      14393  5066

• Operating System and version (Get-IcingaWindowsInformation Win32_OperatingSystem | Select-Object Version, BuildNumber, Caption):

Version    BuildNumber Caption
-------    ----------- -------
10.0.14393 14393       Microsoft Windows Server 2016 Datacenter