Steve, I think the “empty shop” is just a temporary thing that happens when you take the shop out of holiday mode - there is a note on the Holiday Mode page that says items may take a few minutes to appear.
But the shop shouldn’t be empty while actually on holiday. I just put my main shop on holiday mode to check, and all my items are still showing. There is just a note at the top that say’s shop on holiday, and the clicking on an individual item shows it as unavailable to buy.
I’ve attached screen shots below.
When I turned holiday mode off, I got the same message about empty shop that you had. I refreshed a few times - it took about 2 minutes for the items to show.
Maybe it’s worth you checking by putting your shop in holiday mode for a half hour at a quiet shopping time. If your items aren’t showing when actually “on holiday”, try contacting admin.