SSH key-based authentication not working on D-series

I am able to authenticate with my public SSH key just fine on FortiGate 800C and my 448B's.

However, when I attempt to do the same on any of my D-series switches, (224D-POE, 224D-FPOE, 1024D) SSH asks for a password.

All of the switches accept my config just fine, but only the 448B's actually login using PK authentication.