Megalights only supports light functions through the light function atlasing feature, but light functions that mainpulate UV coordinates can’t always be atlas’d. If it can’t be atlas’d, it won’t render with megalights.
This seems to apply to any coordinate manipulation done in the material editor except those output specifically by built-in nodes, excluding material functions… meaning basically panner/rotator will work, but SpiralBlur or even just plugging in texcoord will not… I suspect this limitation is intentional based on the guide, but I’m not entirely sure.
Basically you’re running up against two separate limitations in both systems.