When a VVOL device is bound its associated the SCSI PE device (all secondary level luns are mapped to the PE that they are bound to). The PE device is the one on which the INQUIRY for VPD 0x50 and 0x52 are done to report if the device supports unmap and the unmap block limits. The block limits are mapped to the PE device as a cache of the values returned for the SCSI device (PE). With some arrays it isn't supporting this VPD for the PE device.