iControl returns invalid XML on BIG-IP 5250 BIG-IP_v11.5.1 for get_hardware_information request

I'm querying a bunch of different f5's from 10.1 to 11.5.1 running on different hardware. It appears that the BIG-IP 5250 BIG-IP_v11.5.1 combination returns invalid XML upon the get_hardware_informat...