It seems that when I use tantrum 'E', Amumu doesn't automatically re-target the mob he was hitting prior to using the ability. This isn't a huge issue in team fight situations when I am running around and clicking more often, but more of a problem in the jungle early game.

Example:
Game starts
Choose 'E' ability (tantrum)
Start hitting blue golem
Use 'E' ability
Does not re-target without clicking on said mob

I only recall this happening within the past week or so. It is odd that while hitting the mob to begin with, I suddenly stop after using an ability and just get hit by whatever I was attacking. Has it always been like this and I just never realized? I haven't seen it be a problem with bandage toss 'Q.' It also seems to like to use an extra tantrum without me hitting 'E,' although that might just be due to a sensitive keyboard.

Its not just his E, all abilties that are similar to that, hecs ramage for instance, or kassa's force pulse, morgs dark binding, anything that takes a second to cast, and does not hit a specific target stops auto attacks on the target for some reason, many other champions have this issue, the above are merely a sample