This behaviour was noted in Google Chrome. I was in the Network Profile page when got +10 in a specific community

Network Profile with +10 Achievement

Then, clicked in the "Achievements" icon and clicked again. This usually is enough to have the geen icon with +10 to disappear. As that wasn't enough, clicked in it again and then right click and opened the question that was upvoted in a different tab (as you can see in the next image, that item was clicked as it doesn't appear with a darker background color and the green icon is still in there)

+10 Achievement is still there

In order for that green icon with the number 10 to disapear I had to go to a different page in that same tab. If I did that and went back again, the green icon would still be there.