Hello vir_db!
Please call the VMware-Support-Team.
They were able to fix my problem.
Here's my closed support-case:
Hello Stefan,
Thank you for your time and patience on the Webex today. As discussed, 3 of your datastores had heartbeat corruption.
"A VMFS datastore has a region designated for heartbeat types of operations to ensure that distributed access to the volume occurs safely. When files are being updated, the heartbeat region for those files is locked by the host until the update is complete. The Invalid meta-data status indicates that the content of the heartbeat region is not correct. The subset of files managed by that region are likely to have been locked by a single host that crashed at some point"
Thankfully we were able to repair the corruption (for all 3 datastores) here on one of my local servers.
I hope I could help you and i hope VMware is also able to help you!
Best regards