As far as I know, this is not a bug, or only half a bug 😉
This comes from the new Sport Highlight feature on Blue Sport channels.
If you press down there during football games, you can call up goals and highlights; symbols then appear under the progress bar which can then be selected.
Since the function is only used for Blue Sport channels, I could imagine that this could be fixed in the software so that you can then quickly scroll through the channels using the up and down buttons.
Currently, as @Stauldoteiy82 noted, if you want to scroll down, you always have to go up first and then down.