I have noticed and just confirmed that the Surveil mechanic is hampered by a reducing number of cards you can select from. The first couple of times there are 4 cards to choose from, but suddenly there are only 3 cards to put in the GY. I have seen one instance of just one card.
this limits the usefulness of Surveil, but is it intended?
To recreate just go to the training section and slow play the surveil explanation (3).
//Edited Title -Brigby