I have seen this before if the original production datastore was presented and has been removed, this will result in a PDL on the ESXi host, and in Pre 5.5 the LUN/Datastore will still remain in the list on the ESXi host which will prevent the new DR datastore being mounted.
In ESXi 5.5 there was a new option intorduced which would automatically remove PDL devices.
My question is were the original LUNs/Datastores presented to this host prior to the DR LUNs being promoted?
Simon