I'm having the same symptoms on a pair of Leviton Vizia RF 15A non-dimmers which control my porch & post light out front.
Turning on the lights involves waiting for the full 60 seconds of "Transmitting" flashing. Simultaneously with the "Not Successful" indicator coming on, it succedes in turning on both switches (the two of them comprise Channel 1 on my HA07).
Pressing off on channel 1 turns them off instantly, but the "Transmitting" indicator keeps flashing 60 seconds after the lights are off, again followed by a false "Not Successful."
I tried Chris's suggestion of removing from channel & deleting altoghther and then readding them one at a time & testing at every stage, but nothing works.
Any other Ideas out there?