You had a lead-in and lead-out configured which was causing the loop.
I first created a rectangle of the same dimensions as the image, rounded the corners in Shape Properties, then increased the height to match your original size. I created a rectangle the size of your base but slightly taller then aligned the base to the top rectangle, then applied a boolean union to join together.
I went though those corners a bunch of times, both of them. It would seem to ‘snap’ but would be found when I looked for open shapes.
It would be nice it it would tell you, somehow where it was…
I see a pair of ‘anomalies’, pointed out by the red arrows when ‘selected’ that I don’t understand. They don’t seem to have a ‘middle’ only the two smaller squares. You can grab them and rotate part of the object. Not sure where to look for what they mean.
The markers you’re pointing at with the red arrows are the new shearing controls. Hover over the marker and your cursor will change into a 2-sided arrow which indicates in which direction the shear will occur.
I noticed this same thing. I’m not sure what’s going on there. Even with the snapping the node ends would not join, only be aligned. I ended up breaking apart the entire shape and rejoining the parts which finally resolved it.