Did you mark it as two categories?
I.E. photograph and digital art for example?
If so, you will not show up when they select one media type. You can select two media types, but it's not always to your benefit to do so. Some media categories you'll still show up. If I remember correctly digital art you will, but paintings and photography, you only appear if you selected only that single media type.
PS - It's easier to see how it works on your AW. Go there, click on shop. And then select different media types from the drop down and see what images appear. You can tell which ones you've chosen multiple media types and how that impacts where they appear.