Might your overlays be missing the $decal 1 parameter? It's a bit hard to tell, but this looks like the z-fighting issue that results when the material isn't marked as a decal.
This may be caused by having Camera (top right view) set to 3D shaded textured polygons, if youi change it to 3D textured polygons without the shaded it may stop.
Hoped this helps =)
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