Confirming that this is the fix. To clarify the steps taken, first check enable wireless direct and change the SSID, click Save. Then uncheck wireless direct and click Save. Thanks for this Meilink.
About gave me a heart attack discovering that the radio was still on. It didn't appear to be routing any traffic, but it was still an open connection on our network.
Interestingly, in my building I'm seeing about 1/4 of the available wireless connections are open connections from various HP printers. I wonder if the owner's of those printers have intentionally left these connections up, or if it's a similiar bug to what we're seeing with the M475.