I realized that if I configure some App’s to use sys-whonix, they are not working. If I my sys-vpn then it’s working (and of course it works with all workstations). Therefore I assume this is not a bug & this is intended by design.
Some stand-alone/INDEPENDENT VMs are considered TEMPLATES and it is a BUG /FAUT in Dom0. Change the update policy to sys-whonix or whatever you call it in Global Configuration and check again.