I upgrade to level 14 during a challenge but when i exit the challenge i don't have any reinforcement. Reloading the game i get them xD

I confirm this.

I was also robbed of my reinforcements after I dinged level 14. After it was refilled to 17 I played a single battle against the prof, which left me with 1 reinforcement.

Thanks for the report guys. I've bugged this down for the team to look at.