Shop tile glitch

Just asked on chat and the person I talked to didn’t know either.

I bought 3 rows of shop tiles and placed items on them. Yesterday, I know for a fact that somebody bought from my house store (name was ash1705). I was not in the house when he bought the items (although I was online) and I did not edit the house after I put the tiles down.

I come in today on my main account and see the few bought items are missing, but there is no money in place of them. Trying to pick up any potentially invisible money has no results.

(The colored tiles are on ground layer, obviously)

Hopping on my alt, I test to see if the tiles worked. They do; they ask for the price and trying to buy with insufficient funds fails.

So what happened here? Adding the actual tile price to the unpaid for items, I’ve lost 22,500 and while that’s a paltry amount for some, it means a lot to me.