Here is an example of the AF inconsistency
both shots spot focus point set on the M
these are 100% crops no editing
But what did the camera choose to autofocus on?
The front of the "M" or the back of the "M" or ...?
There are lots of curves and edges in that image (as with the one from TDP) so it isn't clear if the camera is even choosing to autofocus on the same thing each time.
Are sharp lenses like this confusing the camera?
With such a large aperture and the DoF being so shallow, it is entirely possible that the camera believed that both shots are focused properly. Unfortunately we don't know what it is that the camera focused on (or tried to.)