Tahm Kench Ult With Gragas E

I was playing gragas in aram and I had tahm kench on my team. When he would ult I jumped in and instantly e'd to a champion when I got out. I was able to move but I did no damage or knock ups to the champions. I had experienced this multiple times throughout the match and made sure it was an issue. Not even minions were harmed. Please look into this ^-^