Black Screen, chime sounds only

I have seen this behavior a few times now with my Roamio Plus. I navigate My Shows to watch a recorded show, hit Play, then the screen just goes black and the video does not play. After that, if I press the TiVo button on the remote, the chime sounds, but still a black screen. TiVo support seems to think it's due to poor signal to noise ratio and recommend adding a signal attenuator. In the DVR diagnostic screen, I typically see SNR at 38-39 dB but they say it should be 32-34 dB. Anyone else gone through this and seen the behavior go away after adding an attenuator?