First noticed this in ARAM, but it's occurring on SR as well. If Ashe hits you with her E, the vision lasts the normal amount of time but the icon above your head showing that the enemies have vision of you will remain for the rest of the game.
It's a pretty big problem, as then it's no longer possible to tell when you've been spotted by another E or another champion.
just happened in an aram and the enemy team told me (as shaco) and our ally blitz that we were perm visible. harsh break when you're playing a visibility champ such as shaco. we won but i had to out play hard. lol. needs a fix badly.
What champion were you playing? This happened to me when I used Arcade Sona
Did happen a few times, and I can say from experience that it's very anoying having two eyes on top of you while playing 
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I think I finally figured out why it does that. I think it has to do with the person still being in the revealed zone as it disappears
