Game Piece Layers - ignored when item selected?

So the majority of my game board is made up of cards which act as board tiles to be revealed as they are moved into, which I have assigned the Bottom layer. My player tokens (which I want to ALWAYS be on top of the cards) have been assigned the Top layer. However whenever I click on the card below the token, the card goes to the top, hiding the token completely. What have I missed?

FYI: The cards snap to a grid, whereas the token has the ‘Does not stack’ trait with snapping to grid turned off - in case that is causing the problem.

Thanks

Blegh. Restarting Vassal made it consistent, and it turns out I had Top and Bottom the wrong way round in the GPL definition. Whatever is at the top of the list is the BOTTOM layer. Derp.