Migrated Content

Which version of Photoshop are you using? Where are you getting the images? And are you doing anything else to the image besides resizing it? Are you increasing or decreasing the size of the image? Do you have the Eraser tool selected where you might accidentally be introducing transparency?

I ask because I can't reproduce getting the transparent holes in an image after resizing a layer.

The Layer Style stroke will apply even if there's a nearly undetectable 1% opacity spot on the layer created by the Eraser tool.

You might check the image before you scale it to see if there are any holes. You can load the selection by Ctrl (Windows) or Command (macOS) + clicking on the thumbnail of the image in the Layers panel or by selecting the layer and going to Select > Load selection... and selecting the layer. If the marching ants are too hard to see, you can switch to Quick Mask mode by pressing Q or going to Select > Edit in Quick Mask Mode. Holes will appear as red (rubylith) areas. Exit Quick Mask mode by pressing Q again or going back to Select > Edit Quick Mask Mode to toggle it off (the checkmark will go away in the menu).