The UI is extremely buggy. Layers will rename themselves quite often and when upload zones are used they images will often be placed in other locations.
It will not necessarily do this when you are working on the product but can do it randomly hours after the product has been finalized.
The modules that the upload zone allows can be buggy also, so if you select 'designs' only to show, text and upload your own will also show.
Please open a support ticket so we can have a closer look at your issue and help you fix it.