Hello,
it happens to me too.
I have the items imported, I see them in auctiva store, but not in the showcase preview.
The showcase was only in some of my listings, not all. And in those listings with the showcase it had the writing I have no items for sale.
Now I have disabled it.
Moreover I tried to file a support request, but I get an error page:
Server Error in '/' Application.
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Runtime Error
Description: An application error occurred on the server. The current custom error settings for this application prevent the details of the application error from being viewed remotely (for security reasons). It could, however, be viewed by browsers running on the local server machine.
Details: To enable the details of this specific error message to be viewable on remote machines, please create a <customErrors> tag within a "web.config" configuration file located in the root directory of the current web application. This <customErrors> tag should then have its "mode" attribute set to "Off".