when I click the fast forward button the sound is audible at speeds up to 4X but any faster shuttling results in mute. I cannot hear what is happening if I am shuttling at 6X or faster. Is this a bug, or is there some setting which will fix this condition? Any help appreciated.
I don't
think it's a bug, but I'm not entirely sure. I think that this may have been a deliberate decision, based on the fact that the audio becomes effectively unintelligable when shuttled faster than that, but...
...if you use the scrub tool with the Alt key held down, you can shuttle,
and hear the audio a good deal faster than this by moving the mouse a long way over in the direction you want to scrub in, so it's clearly possible to achieve what you want - which is why it
may be a bug!
It's also worth noting that if you want to move about over a file a long way, that the other scrub mode is quite useful too - that's scrubbing with the Ctrl key held down. This will allow you to hear small snatches at any speed you choose to move the mouse at all - albeit in a rather odd way.
I'll log the inconsistency, though, because I don't think it's neccessary to have this restriction.