Sketch 3 - Combining Shapes

Please can someone help a beginner out combining shapes in Sketch 3?

I have the following two ovals (set at 80% opacity so you can more easily see). I would like to combine these two ovals to create a single shape. I think I'm pretty much replicating the following tutorial but I am not getting the same results - Boolean Operations

I am selecting the two shapes (by drawing a selection over them on the canvas or selecting the two oval shapes in the layers pane), and then clicking Union on the main toolbar.

I have posted the before and after. Can someone tell me what I'm doing wrong? Thanks.

Before

After

Update

If I nudge the new Layer named Path under Oval 1 to the right using the arrow key on the keyboard, about 10 pixels it does kind of give me the correct result but the two ovals are then too close together for what I need.