I was following this tutorial but I cannot marge 2 vertex at last or at first. In my first try I managed to merge the first 2 points, but then I couldn’t select anything, not even going to object mode and then edit mode, or selecting, in edit mode, faces, edges, points, nothing.
I’ve tried my scene with Blender 2.83a first, here it is where it doesn’t allowe me to select after mergin.
In Blender 2.82 I tried to reproduced the “bug” with a cube. But now I don’t see the merge at last or at first. How do I make it appear?

This is doing right click:


Ty.