This is a bug for multiple selected items on the corkboard, and it shows up when you select either LABEL or STATUS in the area marked as 1.
If I select a multiple number of index card on the corkboard and select say ‘Concept’ in the dropdown in area 1, only one of the selected index cards will have its label changed. It seems to be arbitrary exactly which card gets changed.
This same behaviour is true if you select a multiple amount of index card and change the STATUS to, f.eg. DRAFT in the dropdown in area 1.
The tick-boxes behave like the drop-downs. Only one index card is changed, and not all selected cards.
When using RIGHT CLICK and the context menu in area 2, after selecting a multiple number of index card, Scrivener behaves correctly and change the status/label of the index card.
I’m on Windows 7.