Findings today:
The height of the image seems to have no bearing on this issue. An image too tall or too small both behave the same in my channel.
The "push down" effect happens not only after sideloading, but also after rebooting the roku.
The "push down" does not seem to happen in SD mode, only HD. But the 1 pixel overlap happens in both SD & HD.
I've tried on 3 diffferent roku models w 2 different firmwares and all seem to behave the same.
A workaround for the overlap is to have at the top of the image a 1 pixel stripe colored to match the overhang - this looks perfect except during the "push down" effect that seems to happen the first time the channel loads.
I tried with a much smaller overhang to make sure we're not in the transition area and I still get the "push down" after sideloading. This has got to be a bug - is it really only happening for me?
aspiring