I encountered this bug while laning versus a Zilean. If I used Sivir's E ability for one of the Zilean bombs then stepped on the other one immediately after, it wouldn't be visible on my champion, but the damage is still taken.
Ran into the bug 3-4 times, although I only noticed it with the Zilean bombs.
Fududles1 votesU'll want to activate e before u get hit by the first bomb and dont bother if its already on you
SyrcD1 votesIt's a visual bug that I've encountered after using sivir's e on the first bomb, then if I were to step on the next it would be picked up but not visible
Fududles1 votesSo you negated the first one by tapping e before it landed and then when he hits you with the second the indicator that comes at you disappears as it hits you ...
If so you should definitely report it to the bug fix team under the support tab