Judy, you are the opposite of slow :-)
Okay, forget about AW2K and just look at the regular Ebay SYI. When you get to the "Add Pictures" section, and select to add one or more pics, you get a pop-up window with several tabbed upload options. On all the tabs (other than self-hosted) there are 2 "Optional Picture Upgrades" on the bottom of the screens, each with a checkbox. The first box is "Gallery Plus" and the second box is "Picture Pack". If you click on the (?) for description, the picture pack mentions the Zoom feature within the listing. I'll see if I can attach a screen shot to this message.
I'm using the Collectibles category and do have a premium store - not sure if that matters - but both upgrades say "free" to me.
Let me also mention that I am no longer self-hosting any of the pics since I no longer put item pics within my listing descriptions - it totally messes up smart phone formatting, and the ebay top-screen galleries are highly optimized for mobile.
So what I found was simply this. If I let AW2K upload my ebay-hosted images, they will all appear in the listing gallery, but none of them are zoom-able. If I revise the listing, I can add a photo to the existing photos, and even though both picture upgrades are checked, only the new photo is zoomable.
It acts as if the "picture pack" toggle is not being activated during the AW2K upload - OR - the picture is being shrunk to fit the standard gallery size. I don't use any AW2K photo reduction and upload at the highest quality, so I don't think it's that.
Let me know if this makes sense...lol.