Select some photos in grid view, partly with PV2010 and partly with PV2012. The quick develop controls display for PV2012, but are disabled, which is logical because of the mixed PVs. Everything is OK so far.
However, the clarity controls are still enabled, and they apparently change only the photos with PV2012 (including resetting clarity by clicking on the label). In this situation with mixed PVs selected, the clarity controls should be disabled, too.