I'm having this issue on vSphere 6.0 Update 3, so it's not solved in any updates mentioned in the KB.
I think our hosts never run 5.5, but I'm not entirely sure about this. I am, however, sure that this problem prevents me from decommissioning our old iSCSI datastores.. Let me know if you have any tips, I have run the esxcli commands recommended, still need to see if a reboot fixes this (KB didn't mention anything about a reboot).