Hi cathyn,
I just tested your listing here and also tested it with the eBay’s mobile friendly checker (“i-ways”) and get a perfect result.
My guess is that eBay’s internal mobile checker doesn’t browse through the whole source code.
Do you get a specific error message why they think it’s not mobile friendly? Can you maybe make a screenshot of the mobile checker?
Just an idea:
If you insert the following code into the “footer” field in the GarageSale preferences > General and invoke the revise command, does this make any differences?:
<style>img {max-width: 100%;}</style>
Regards, Kristian