Backup of VM's fail because .VMX file is locked

Hi all,

We have an environment of 5 ESXi hosts all connected to an iSCSI SAN.

we use Veeam Backup and Replication 6 to backup the VM's.

Most of the VM's get backed up ok, but some fail with an error that the .VMX file is locked.

The .VMX file is indeed locked. The VM is powered on. From vCenter, when I browse the datastore and try to download the .VMX file I get an error saying the file is locked.

VMX files from other VM's I'm able to download without problem.

When I power off the specific VM the .VMX file is unlocked. After power on the file is still unlocked.

But "after some time" the file is locked again and so the VM cannot be backed up. Why is this happening to some VM's and not to others?

thanks.