I have had FIOS for a long time and I am just now experiencing outages with MC. I went through the guided troubleshooting where I rebooted everything with no luck. I the called CS who went through the same again and finally scheduled an appointment. Just before the appointment, the channels came back so I cancelled. This past week, it is randomly working or out.
I went outside and tightened the connections on my splitters. I have two TVs and the problem occurs on both. No other channels are affected, including a channel that I get above the MC channels.