Minor issue with the apps:
Any station acting as master station performs its specific functions (RF or remote) as well. However neither the mobile nor the web app allows setting these function on a station configured as master. The workaround is to remove the master settings of the station, change the required specific functions (e.g. RF code), then apply the master settings again.
The apps should present the actual specific function settings and allow the change of them.
Thanks for reporting. You are correct if a master station is set as a RF/remote station it will perform the special functions but the only way to set this is when the station is not set as a master. So there is inconsistency between the firmware and the app.