When you enter the store the items are put on the Inventory layer which is layer 10. When you return to the level the items move down to the Buildings layer which is layer 10. If you are using global layers they need to match throughout the game in terms of number/index so they should match between all layouts. Think of it like the items are positioned on a numbered layer rather than by name.
You could create a work around such as 'on start of layout' set invitems layer to "Inventory" but that is kinda forcing the position and soon it'll get overwhelming as you add more things that you need to force the layer position etc and bugs may occur, I believe the best practice is to match layers across all layouts then you can take advantage of their global-ness.