"Personal Property" is a legal description for property that is tangible (unlike intellectual property) and movable (unlike real property). It is not a description of ownership.
If someone sticks a gun in your face and takes your leased car were you not robbed? The fact that you were not the legal owner of the car is irrelevant when you have legal possession.
when you have legal possession.
In this case you sadly missed the point that the item was taken within the physical confines of the store and that the “legal” possession of the item was that of the store...not the shopper who had yet to transfer “legal” possession of the item via actually paying for it and removing it “legally” from that store’s ownership and inventory.
If assault was involved then the assault was a crime but theft did not occur due to the fact that she was in fact simply moving the inventory of the store around within the store until she actually bought it and it became her “personal” property.