Well, I'm having a very strange AF problem with my 7DII + 18-135 STM. Check this out:
I did AFMA, and it was already pretty close (+3, -2).
With center point, it nails focus in both portrait and landscape.
With side points (left and right), in front focuses in landscape.
In normal portrait (right hand on top), it dramatically front focuses with an edge (top) point.
In reverse portrait (right hand on bottom) it dramatically back focuses with an edge (top) point.
Canon thinks is a decentering problem with the lens. They may be right since it nails focus with my 70-200II in all orientations with all points. But I don't understand how a decentering problem would manifest differently based on orientation and why it's sharp across the frame with the center point.
Is that strange or what?