I'm having similar problems; I run wagic on pc with high quality images, and in 0.16 i had no problems at all, but in 0.17.1 card images seem to have all kinds of issues.
If i use old style image zips (m10.zip, m11.zip ,etc) the card previews of your hand cards (right side of the screen) are missing. If you select the card so a magnified version comes up on the right side, the magnified version shows a correct card image.
If i dump all the cards into 1 big zip (the image.zip method) a weird thing happens: All sets alphabetically above MBS work, and all below do not. My images.zip is 4 GB (high quality images!), and since the MBS images seem to be about halfway in this file i have the feeling that there's a 2 GB limitation on this images.zip file that wagic can reconise, and all cards stored above the 2 gb mark cannot be read. Or maybe i'm completely wrong
The only thing that seems to work so far is to just unpack all the jpegs and not use zips at all; i have had no problems this way (except having 41000 jpegs on my disk).