_+What I expected to happen was...:_+
There would normally nothing.
_+What actually happened was...:_+
We can see a grid with void blocks.
_+Steps to Reproduce:_+
_1._ Set a blank texture(here filled_map) in your resource-pack.
_2._ Go in a map and see in a map.
intended, the void isn't any blocks, the blocks above are air, which are ignored by maps, thus it shows the block grid instead