This was brought up by quite a few people in the forums and I wrote a bug report here.
I guess current thinking at Roon is, that this is “by design” and not “by bug”. The reasoning goes along the lines of “easier in portrait mode”. Maybe they rethink - dont know. I think it looks terrible. Movements are indented everywhere. Booklets of recordings, concert programs, you name it… You just no longer easily see where a composition starts and ends.
The composition matching issue you experience I think has been brought up before as well. Just cant find the link right now. I put it in when I find it.