My areas of incompetence would be too long to list in full, and as a rule I am not happy with my work, or when I am I am not really sure why, which in itself I analyse as a sign of incompetence.
AF continues to baffle me, but I have a Nikon Df with an add-on split-screen, and my main lens is a PC-E 24mm, so I do not worry too much about AF Even though the PC-E is my main lens, I am sure I do not have the competence to master all its subtleties, far from it.
Probably my main incompetence area is post-processing. I have spent a lot of time with Photoshop, purchased online training, a Wacom tablet, I read Adobe's reference manual, and I still don't have a clue and am unable to reproduce what I am taught. So for the moment I use DxO Pro which is much less intimidating.