Mm. Probably just somewhere hidden in the back and they found it mid-day.
The City Walk store was completely empty by 5 PM on Sunday.
The Entrance store had some stuff, but not a lot upon entering.
The one by Castle Theater was pretty much the same as the entrance.
And the one on the Lower Lot had the most stuff, but it was still fairly limited. The way I got my tumbler is they randomly pulled some stuff out of a box and put it on a shelf, only to be swooped up INSTANTLY by anyone who was nearby.