WiFi.scan() returning 0 networks when no credentials present

I am basically using the standard implementation of WiFi.scan per the docs populating an array. When I’ve connected my device to a network using ‘particle serial wifi’ everything works fine and the scan returns 20 (size of array) networks. However, if I hold down the setup button and clear the credentials, then restart my device, then WiFi.scan() returns 0. Does having or not having credentials change the way scan works?

Photon device OS 1.0.1?
Argon device OS 0.9.0
anything else?

Photon v1.0.1 yep