#1

After having checked the career unlocks, and looking for Ambra’s unlock conditions which are either rank based ‘or’ by playing five matches as a Jennerit character. I played six matches as Rath in total, as he was the only one unlocked at the time. After this, I did not get the same unlock notification as I received for unlocking Shayne via playing five matches as anyone.

#2

On the same note, I’ve killed 50 players to unlock Phoebe, and the challenge says it’s completed, but she’s not unlocked for me to play. Similarly to your issue, I didn’t get an unlock notification for her either.