Low power on steep climbs

Hi

Today I rode the alp. I’ve ridden it a few times, but today with my new kickr 6. Trainer difficulty is set at 100%. Whenever I hit a 7%+ incline, as my cadence dropped, so did my power. Usually power would increase as you grind through it. Once I stopped and restarted climbing again, the power went back up as I started spinning again but once the incline kicked up, the power dropped as the cadence decreased. My legs definitely felt like they were putting out more power than what zwift was saying. Is this a known issue?