Assuming you get your tuner back - can you lock onto any channel (stream via VLC or similar)? If you can get the channels then you should get the EPG... the lack of the latter means we'd need to test the former... the fact that your tuner then disappeared might be related.
If you can get a channel, I'd test one channel from each mux and see if it's a failure of something specific. And if you still don't get the EPG... well, there's always xmltv instead...!Channel 4 HD