I'm having this issue too, but it's definitely not that the hard drive has not been found as it appears in the list of devices. The most annoying thing is that it seems to be intermittent, sometimes it works, more often it doesn't. Sometimes when it doesn't work, it 'forgets' the whole series, other times it is still there showing I have selected it to record, it just doesn't.
I do feel it's a power management issue, but really annoying that you basically have to be at home to make sure it's awake and recording! Defeats the object. I haven't yet tried a new hard drive, but I'm reluctant to as it seems others are having the same issue. This was one of the main reasons I bought a smart TV so I'm very frustrated.
