This could be caused by several reasons. Generally related to an update or installing another embroidery program after you installed Hatch.
1. If you have a lot of designs, it may just take a bit of time for your computer to render all the images.
2. If you have another embroidery software also installed, it may have captured the "ownership" of that icon. Especially if you have installed it after you installed Hatch.
3. You may just need to re-index your thumbnails. See the details here:
4. There are several other reasons this may happen. Go to the FAQs and type in Thumbnails. here is a quick link: