FL50R on EM-5 hotshoe not working?

Do other Olympus flashes work on the cameras. There were issues with some E-M5 hot shoes. Mine needed to be sent in and replaced. Was actually replaced with a bit different unit. The idea that two cameras don't work seems unlikely, but... If the flash works on the E-5 it might be that both of the E-M5s have the same issue. Hope I'm wrong. Didn't take long to get it fixed but it was irksome.