Heimerdinger has received multiple bug fixes in the League of Legends Patch 8.24 Mid-Update.
League of Legends Patch 8.24 brought changes to the ranked system as well as balance changes to multiple champions including Heimerdinger. Some of those changes have caused massive bugs for the champion.
"E - CH2-Electron Storm Grenade and UPGRADE!!!'d E - CH-3X Lightning Grenade stun durations have been fixed. Q - H-28 G Evolution Turret's third turret charge is stockpiling no longer allows Heimerdinger to get a fourth charge. UPGRADE!!!'d W - Hextech Rocket Swarm once again shares a cooldown with W - Hextech Micro-Rockets. Heimerdinger can no longer cast UPGRADE!!!'d E - CH-3X Lightning Grenade immediately after E - CH2-Electron Storm Grenade if timed exactly."
It's no surprise that a few bugs were found in the latest League of Legends Patch 8.24. but the amount that bothered Heimerdinger was alarming. Riot Games had to release a hotfix just to resolve the issue. There were new ranked changes made in the latest patch as well.
Photo courtesy of Riot Games