Can't drag templates over images

I am attempting to drag a udt tag with an associated template over a background image. Upon doing this I get a message saying that I am attempting to bind a tag but the binding is set to string. If I remove the background image and drag the udt onto the empty page everything works as expected. The way I am currently getting around this is by dragging the template first and then dragging the udt onto the template. Any ideas?

As a temporary fix, you can put a Container on top of the background image and make the Background Color transparent: 238,236,232,0