My New Fire Cube arrived late this afternoon and I have just spent the evening setting it up and I can confirm the HD channels with interlaced h264 seems to be working perfeclty with hardware transcoding.
However at this point I am not 100% sure as the hardware / software option does not seem to be avaialble to the cube? Am I right to assume this means it is defaulting to hardware?
If so I can confirm the issue is not present on the cube like it is on the 4K Stick, the only issue is the black screen with sound only on the SD channels which I believe is related to the .13 build of Channels not a cube issue