A bug on the profile

I am playing the game on EUW and the game is english, I have Yasuo level 6 and on the right of the top 3 champion masteries. I'm Silver V. The "bug" occurs when you go and place your cursor onto the Silver V league. Then you need to go past the honor things without touching anything and then go on the champion. Then the green text under the white one doesn't have a black background. It doesnt happen when you go on something else with the cursor. And after you place your cursor on something else it has a black background again. If you do the same thing again it happens again. Note: it works on other champions too, but the champion has to be level 5 or 6, otherwise it won't work.