we have vmdisks with thin provision with Netapp nfsv3 where san disk space auto reclaim is not working. VMs migrated but still and now no data on volume but still space is showing as occupied. Any inputs on it pls. Ontap is 9.1

we have vmdisks with thin provision with Netapp nfsv3 where san disk space auto reclaim is not working. VMs migrated but still and now no data on volume but still space is showing as occupied. Any inputs on it pls.    Ontap is 9.1n