The answer is 54.8% (or 0.548), how do I know? The tricks is to export the gradient to SVG, open it into a Text Editor and look for the "offset", it would be something like this:
<stop offset="0.548" stop-color="#46addb"/>
This is really important to convey to a developer how the Gradient should be configured on code.
Glad to hear you’re sorted! Have a nice weekend.
I figured out what was the problem. I was marking for export assets inside an art board that wasn't connected to anything on Prototype. I fixed it by adding a link to the art board from the Home art board.