The gradient isn't filling the whole polygon and I have no idea why.
Or wait a moment. After some fiddling with the width and reverting it back... it seems to work. Is this a bug?
#How to use a Gradient texture with Polygon2D
tired pine
At least the editor showing it all black was a bug. After running the project it reverted back to its usual partial-filledness.
Not that it took much setting up, but here's the sample.