Great! Glad that worked for you. I think using a "blank" image, and then expanding it, was probably the issue here - the placements, scales, etc. can sometimes get screwed up.
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For anyone who's interested I find that dragging and dropping cards directly on to the image too far right (nearer to the right border of the window) they tend to disappear; which most times means just dropped off screen). Dragging and dropping from the deck to the left side, always drop where expected.
I tend to drop all cards to the left and then move them in to place without any issues or 'disappearances'.
To sum up, dragging directly from the deck to the right of the window has cards disappear. Dragging directly to the left is okay. Dragging within the window is okay.