Keying an anchor point is a lesser known option for aligning and distributing.

Clicking an object in a selection to key it is a thing that can be learnt by a chance (that is how I learned it myself), but using the latest selected point as a key is not a behaviour that is easily noticed.

The change of the mode is marked only via the small icon in the corner of Align panel, and nothing else on the artboard tells about it — compare this to the fat edge a key object uses.

Can you try to make a key point somewhat more visible?