GrayscaleRange, Bit mask will only let you extract a single bit from the mask. most likely it worked but the slice it extracted from your gradient was razor thin so you didn't see it. If you want to extract a certain range the math is pretty simple.
ExtractMasks - All the inputs are plugged to the output of the final lerp of the previous screenshot. At this point the material is already functional; the masks we got can be used to paint the material with your textures. Next post - fine-tuning the material.
UE4, Blurred glass material (3/ 3) by RyanB - turns out the tempAA dither thing really needs the dither texture in addition to the math pattern offset. Makes the spec patterns much smoother except at very far distances: forums.unrealengine.com/showthread.php?70143-So-Blurred-glass-material-is-impossible-in-Unreal-Engine-4&p=292956&viewfull=1#post292956