Hi,
got the issue figured out in our non-vcsa environment. After going through several reinstalsl, throubleshooting hours, i found 2 hosts acting weird (not reporting performance or inventory data). Reinstalled both hosts and the inventory service runs fine! Seems the service was waiting for the hosts to get back to it and didn´t want to go on with refreshing inventory data until the hosts reported their data.
Weird stuff going on with the inventory service 
Greetings from Germany
Marcel