Sometimes I cannot send tokens behind or in front of other tokens or images. There does not seem to be any consistency in what kind of image is used for the token (jpg or png) except that the problem does not occur if both tokens are from the marketplace. I have tried this with multiple images, both linked and unlinked, and with "Enable Performance Enhancements" turned on and off. This happens in both Chrome and Firefox and also in Chrome Incognito mode.