When a product page is loading, all of the images for the listing will appear in the row of thumbnails, but the last thumbnail will disappear once the page is finished loading. I've looked at product pages in Chrome, Firefox, and Internet Explorer on different computers and it looks like it's only affecting Chrome.
I wanted to alert other sellers in case their last photo holds important information. I'm currently advising people to use another browser to view the images, via store message banner.
I've already contacted Tindie support/Amber. I figure they're out of the office for the long weekend in the US though.
EDIT: Gif of a page refresh right now in Chrome...