Can you post screenshot with Layers panel? Where is drop shadow? On separate layer? Is that layer normal layer or Smart Object? Is layer with drop shadow masked or clipped to some other layer? Is it in group of layers with mask applied?
I have used a mockup psd file which I cant upload, as the file format is not supported. It would be good to soften the edge of the drop shadow of the psd so I could generate all the files again. Thanks
It looks to me like the drop shadow was applied too close to the cropped edge. Can you redo it making the canvas size larger to include the whole drop shadow instead of cropping it off with this sharp edge?
You can also make the drop shadow into its own layer (right-click on "FX" and from the dropdown menu choose "create layer") and then erase around it if you need to, using a large soft brush.