Can confirm that I need both commands:
iwconfig wlan0 mode master
Not quite sure why as obviously the hostapd service comes up on boot and the
/etc/network/interfaces file has that exact mode setting line. But the bridge comes up with the wireless card disabled and while the mode setting line will enable it, it requires the hostapd restart to work.
Anyway, the fact I know what to do means it is easy to restore the network to full capacity, but it would be nice if it worked off-the-bat.