How critical is it to have one on the antennas that have left and right hand polarization connections on the back? I don't have one yet for my antenna but will next week. I guess reception will suffer?
Basically the load is to complete a circuit. Apparently from what you are saying, both ports in the back are wired together and leaving one open will not work that well and will cause issues. I have no idea on FPV, but on Coax, like your home TV runs on or your internet, you have to run a 75Ω resistor to plug any open ports in a splitter that are not being used. If you don't, you will have signal degradation which is what I suspect is happening to your system.