Created a new PBE account, proceeded to play tutorial. Switched through each Champion after killing an enemy champion in this order: Miss Fortune -> Master Yi -> Lux -> Ahri -> Darius.
Upon switching to Darius I received a skill level up prompt. Darius seemed to spawn, but gave no vision and was uncontrollable (though somehow I was able to use Heal despite it being greyed/x'd out). The game stayed in that state until I exited the tutorial.
Reproducible 3/3 times following the above steps. Switching champions in a different order did not seem to cause the issue.