I'm not sure, but this might be a VMware bug.
Running get-vmhost | get-scsilun | get-scsilunpath from PowerCLI returns errors such as "Variable Cannot be null".
I successfully ran the command on vCenter version: 5.5.0 1750596
I could not run the command successfully on vCenter version: 5.5.0 1891313
PowerCLI 5.5 R2 U1 was the powercli version run against both vCenter versions.
Also, the vCenter version that did not work, had EMC's PowerPath on the ESXi hsots, which could be the issue.