Singed's E ability does not work reliable

The "Throw" (E-Spell) of Singed is buggy. Sporadically (felt chance of 30%) it does not work correcly. Singed turns himself in a circle and the enemy is thrown up in the air on the same place, not behind him. The Ability is useless this way.

This bug gives me cancer, plz fix it fast.

Thank you in advance