Orange pi zero - wifi packet injection does not work unless any wireless interface is associated with access point

Hi all, its probably something simple but here is what i am struggling with:

airmon-ng start <interface name>

iwconfig wlan1mon channel 13

aireplay-ng --test wlan1mon

ifconfig wlan0 up -> wlan0 is configured and connected to the access point

packets are injected and can be observed with another machine  

ifconfig wlan0 down / or not associated with network

packets are not injected and cannot be observed

aireplay-ng  or  raw  socket directly  shows no errors

initial toughs somewhere there is a switch to enable/disable radio at low level

nothing obvious in strace  tried with and without network manager.

tried with internal and 2 external wifi adapters at lest one has to be associated

advice on next steps tracing this down is appreciated

realized while writing this that channels might be an issue and indeed only channels 12,13 are affected

iw reg get
global
country 00: DFS-UNSET

 iw reg set JP
 iw reg get
global
country JP: DFS-JP

and it works like dream

it seems all I needed is rubber duck to get through this one -  thanks to the forum and maybe someone will find this helpful