I think it's a bug

While playing around with my new Lucian skin I ulted a minion wave as it spawned and some of the minions because untargetable/unkillable. These minions sit next to the inhibitor and appear to get stuck there. Friendly minions ignore them as well, and you're still able to run into them.

https://gyazo.com/60ba755f789ab3520a70c2a403f5a373 (Image of friendly minions ignoring them)