iOS 6 Bug? VIP feature doesn't work w/ ActiveSync mail

I noticed that the new VIP feature doesn't work against ActiveSync mail. The feature works as advertised with my Hotmail account, however.

I am able to select VIP users from within my AS account but their emails are not being filtered into the VIP folder. I do get an audio alert however when their emails come in.

is this by design or is it a bug?