I repeatedly find myself in positions where I attempt to pick up a 
stack of cards in proper order, but am unable to do so (only the card 
I clicked appears, and the stack cannot be moved).

This most commonly happens when the shuffle coincidentally lays the 
cards in proper stacking order, but also seems to occur when I move a 
stack onto a card, and then try to lift the "new" stack to another 
place.

Am I missing something?