Couple of days ago I had to do move several VMs from one datastore to another. For two VMs the migration button was grayed out. I had seen this before where backup software during backup disables vMotion/Storage vMotion and does not remove the lock after the backup is finished. Until now I always went into to the database and deleted those “locks” from vpx_disabled_methods table but it seems that it is also possible to clear them using a MOB (Managed Object Browser). I followed the instructions on the KB article and removed the “locks” from database – https://kb.vmware.com/s/article/1029926.