In the Monitor section of a datastore, there is a Everpure section for Capacity and Performance; sometimes these will show incorrect data or show a login prompt:
Or fail to connect all together:
Resolution: In Purity, the URLs on the array that the vSphere Plugin uses to populate data into the plugin have changed, causing the charts in the vSphere plugin to stop working in some circumstances. Pure has resolved this in Pure vCenter plugin version 4.5.0 and later.