Zac gets sad when slowed during E - Elastic Slingshot

Zac doesn't go as far as intended when attempting to use E - Elastic Slingshot and having a slow landed on him. Bug is easy to replicate: charge Elastic Slingshot for any distance other than point blank range, then have any sort of slow land on him. Most recent case was the first half of LeBlanc's E - Ethereal Chains landing just as I attempted to slingshot into a vayne. I understand abilities like Blitzcrank's Q - Rocket Grab "catching" Zac midair, but having the range of an ability reduced by a slow is ridiculous.