Gahh. I just noticed this.
Alps RK09K 9mm vertical board mount pot footprint:
Alpha RD901F 9mm vertical board mount pot footprint:
Spot the difference?
It’s not as if Alps uses that pin numbering. From https://tech.alpsalpine.com/prod/e/pdf/potentiometer/rotarypotentiometers/rk09k/rk09k.pdf:
Weird.