Thanks for answering!
The problem is indeed there is a Veeam Temporary Snapshot hanging on the VM.
But the Veeam backup jobs don't run anymore.
The current task in the summary tab is: "Create virtual machine snapshot, Create virtual machine snapshot, Create virtual machine snapshot" (3 times)
As I try to remove the snapshot through Snapshot manager I cannot delete it, even when Veeam is stopped completely.
Go to, delete and delete all is greyed out.
