Felix Griffin's Editor Mod
Doesn't work on the top side. I had 2 drawbridges in a horizontal position and across from each other, forming a 3 square wide surface. Bounce gel had no effect across the entire 3 square surface (so not only the square where both bridges touch).
This is also in Original Portal 2 style.
To illustrate both issues:
Bouncing gel

None of the bouncing gel placed across these draw bridges works, simply doesn't bounce.
Lighting


As you can see the top 2 draw bridges are much darker than the bottom two.
When turning the draw bridge setup 90? the lighting issue does not turn. It is clear that it relates to orientation and not to placement of any item or light source, as you can see here:


If you need any more screenshots or want it tested in other styles let me know.
As always thanks a lot for your time and effort!