We have a RB133 and are configured as: Backhaul, Bridge, Hotspot Radio and Lan (ether1). Ether2 and Ether3 are not used. The “R” shows in the lefthand column for all but the Hotspot Radio. Under Bridge, Ports. Hotspot Radio, Status. Port 2 Role is shows “disabled port”. How do we enable Port 2? 
The “R” at the left column under Interfaces shows for everything but Hotspot Radio. We use an Imbiquiti XR2 for the backhaul radio and an Imbiquiti SR2 for the Hotspot Radio. We had one of each card and didn’t want to spend money to have a pair.
What devices are in the bridge? What device is #2?
The AP radio will not show an “R” until another radio connects to it.