How to make a smooth rectangle shape gradient from solid to transparent

I've tried 3 different ways to do this simple task. I'm new to After Effects, so I know this is a noob question.

All I want is to have a rectangle that starts a solid black color from the left, and has a smooth linear gradient

to the end (to transparent).

As you can see below, gradient fill color panel represents what I want (smooth and linear from left to right, black to transparent),

but the shape itself is solid until it gets to the middle, then does a quick gradient and doesn't reach the end of the rectangle.

What am I doing wrong?