Gradient appearing invisible or incorrect in final export (video demonstration included)

Here is a video showing what I mean: https://www.youtube.com/watch?v=B_qmA-TeUmc

I added a live gradient layer which goes from 100% Opacity Black to 0% Opacity Black near the bottom of the image. But upon export, both in the preview and in the actual exported file, the gradient does not appear. When I rasterized the gradient layer, it did appear as expected.

Here's a second recording with some additional strange behavior that might hint towards a cause: https://www.youtube.com/watch?v=szjFXp8yoB8 

It seems that the scaling setting of the gradient may be involved? It seems that the gradient is not totally invisible, but perhaps behind the scenes, the scaling for it is off, or it is mis-placed somehow. I can't be certain, but it seems like when the gradient scaling is set to 100%, it appears correct.