Radial gradient becomes oval when rectangle frame is vertical

1) Version: InDesign CC 2018
2) Draw a vertical rectangular shape and insert a radial gradient
3) Expecting the gradient to be a perfect circle.
4) Actual result is an oval gradient that is impossible to change into a perfect circular gradient, even when holding the Shift key while using the Gradient Swatch Tool.
5) No matter what I do, the gradient remains an oval, unless I stretch the shape back to a square or a horizontal rectangle.

The only annoying way I found to temporarily solve this problem is to rotate the horizontal rectangle 90 degrees. This allows me to use the Gradient Swatch Tool as I wish to create a perfect circular blend anywhere in the rectangular shape.

Any solution to this without having to rotate the shape?