This has been happening to me since the patch yesterday. When I go into my skills or my inventory the buttons for the champion bar also appear. Like the original poster screenshots above. In the skills section for example if I hit Y to barswap it takes me out of skills and into the champion screen. the only way I could resolve it was to hard quit the game and relog. I think this only happened after I had updated my champion bar active skills. But I had committed them and exited the champion screen so I'm not sure why this was happening.

Also when I change an item of gear and hit back in stead of taking me back one screen so I can move to the next item of gear it takes me out of my inventory to the main menu. Not sure if this is related but thought it sounded similar as although the inventory taking ages to select and item of gear and jumping about, the backing up to the main screen has only been happening since yesterday patch.

I'm Xbox EU

I had this yesterday on XB NA for the first time, I did a /reloadui to resolve the issue. It did not return for the reminder of time l played. Haven't logged in today yet to see if it returned.