Fizz Rework - Ult has a cast delay (random)

The new Fizz rework's ult is a bit bugged.

Played a few games with him, and when I cast his ult, 4/5 times it will have a cast delay of about half a second to a second. The other times it's instant.

Please, please look into this ASAP. It's almost impossible for me to get any ults to land properly since it's randomly delayed now.