I recently bought the Foxsat HDR and a new 80cm dish with an Octo LNB. All worked fine for a couple of weeks - signal strength 100% and quality 90% on both tuners.
Then about a week ago, the unit reported "No or Bad signal" on some of the channels but not all.
a thorough check today shows that I can see all of the horizontally polarised channels and none of the vertical ones.

Rebooting makes no difference, but turning the unit off at the mains recovers the missing channels (or some of them) for a few minutes, but then I lose them all.

Has anyone come across this before?. I understand the set top box switches the polarisation of the LNB by changing the voltage output. Maybe I've got a duff LNB?, or duff foxsat? or something else?

Any thoughts?

Well if you have an Octo LNB and can get at it you could swap the LNB's in use and see if that makes a difference.

The usual first response to wierd symptoms like this is the factory reset.