Max MV Memory Contention

For some reason, in my single vRealize instance monitoring 1 cluster of 6 hosts running 5,5 u3b, I never see anything but zero for the memory contention counter, which translates into dashboards that are probably somewhat deficient when generating an overview of cluster health. Am I being daft and missing something here, or is this metric simply not being collected for some reason? Other metrics seem perfectly realistic, e.g. CPU and Disk Latency (see attached screenshots).