Hi Bartek,
Did you add any authentication header when calling the action?
My first guess would be that you are trying to call the action but get an authentication error. Try to view the logs of the individual activation's.
aio rt activation list
and then
aio rt activation log <activation_id>
There should be one related to the authentication and one related to your action. Maybe share your list with us so we can be of better assistance.
Regards,