Polar Vortex bug

I finished the first set of challenges for the Yetis and obtained all 50 stars necessary to progress but I never received a “boss key” and can’t move on with anymore of the Polar Vortex challenges or bosses. I’m unnecessarily missing out on potential players and rewards to upgrade my team. Any kind of response if update would be appreciated. Don’t want to quit playing the mode like I did last year because of bugs and glitches not being fixed with no response from devs or anybody.