I think it is a bug.you can refer to VNXe OE release note and upgrade to the lastest version.
In vSphere, I unmounted and detached 2 older datastores that I no longer needed.  That part went off without a hitch.  Next, I used Unisphere to connect to my VNXe3300, browsed to Storage > VMWare.  I selected datastore, clicked delete button, responded yes to the confirmation.  VMWare window refreshed and the deleted datastore is gone.  Now, the problem:  the available space on the storage pool does not reflect that the store is gone.  The deleted datastores were 2 TB each.  Storage pool for these datastores reflect a free space of 1.2 TB, which is what it was prior to deletion.  The odd thing is that the LUNS still appear in vSphere after a rescan and I can mount and attach the datastores back and browsing to the datastore show me that it is indeed attaching properly.  Any one have any thoughts on getting these deleted when they don't appear in the Storage > VMWare list?
Deleted VMWare Datastores, not really deleting...