Veigar Dissappearing Bug [Gameplay]

So After a normal blind pick game. I am playing as adc jhin while a 2 v 5 scuffle when down with me and ahri . The enemy hecriam charges down our ahri and dies to her. Then the enemy veigar shows up and takes down our beloved mid laner. After viegar rotates to me I swiftly put down a trap to retaliate his magical power, but he vanished and while he was off the rift he tripped my trap while invisible therefore unhittable. Then after I started to act my final scene of the play but, he vanished again! Thus I could not hit the dark mage making him live and ruining my performance. I recorded the act going down but I dont know how to upload it. So if you guys can tell me that would be a great help.