Issues with item file upload and ajax file upload

-- url of the page with the problem -- : www.willowcreekgraphics.com/
-- HikaShop version -- : 2.6.3
-- Joomla version -- : 3.5.1
-- PHP version -- : 5.6.17
-- Browser(s) name and version -- : Firefox 47.0

In testing we discovered that using the custom field type "File" allows a customer upload to overwrite an existing.
Though the field type "Ajax File" creates a unique name, it's not intuitive.
The text on the product detail page indicates:
"No image - Drag & Drop here or use the upload button"

This should probably read "file", not "image" to avoid confusion (not all files are images).
There is no upload button displayed - though the customer may discover in experimentation that the field label is clickable to trigger a "Browse". This is shown in the first attachment.
There also isn't a visible drop target displayed for the customer to drag and drop files to initially...so they have to guess on where to drop files to within the page.
If they drag a file over the right element through experimentation, then the target will appear (as in the second attachment).
Thinking this may be something template related, I tried both Beez and Prostar, and set Hikashop configuration display to "None" for both styles and front-end CSS.

Is there something else I'm missing to make this work?
Should the "File" custom field type allow one customer's files to be overwritten by another if they should use the same file name?

Of course in my testing I was using the same file and didn't think about Hikashop checking the file content. Very clever!

Since it appears I can use the "File" type, that gives me time to figure out what there is on my site that causes the Ajax file target not to be displayed. I've already confirmed it's not template related, so will start disabling other extensions to determine the cause.

Thank you Nicolas.