Neato, that pinout image is wrong. Apparently pin 11 and 12 are backwards. Wow.
Here's a correct one.
So Pin 13 and ICSP-SCK work interchangeably, as does Pin 12 and ICSP-MISO.
However, for some reason, Pin 11 isn't working with the MOSI. And I checked this on 3 different Nanos.
Is there something special about Pin 11/MOSI?