Shader textures on floor bugged on automap

[camaxide]

The automap is able to show shader textures on the automap like shader liquids etc.
However it is currently bugged. when having textured automap turned on and for instance looking at a yellow lava - the lava floor will simply render as a plain yellow fill instead of showing any texture-data.
but, if you get outside of the map (clipping) the currect shader texture will often suddenly render correctly - it will then even be animated and all just like the shader surface ingame.. clipping back into the gameworld will return the shader floors back into plain yellow fill.
https://youtu.be/Q3MTttT0Eec
This video shows it in action.
I also notice that moving from the north ledge (higher point) and down to the lower floor the shader pops into view for a microsecond - so perhaps all thats is wrong is the way GzDoom calculates the depth and when to render the shader surface.. as if the player is in the wrong height for it to render.. but it should really render the same as any other surface.
In the youtube clip this is a 3D-floor - but it behaves the same if it's just the normal floor as well.