Kickr power increase uphill

I’m new to Zwift (about 1 month). I have recently noticed that the Kickr seems to significantly overestimate my power output up steep hills. For flat rides and hills less than about 10% gradient, the kickr power and my assioma duo run within about 2% of each other which is obviously more than acceptable. When doing the radio tower climb for example, the difference can be 20-30% (50W+), with the Kickr reading higher. I feel confident the Kickr is incorrect based on perceived exertion and my inability to maintain this purported level if power.

A factory calibration of the Kickr didn’t help. I’m not sure if anyone has had a similar experience.

Which Kickr model do you use?

I have noticed the same with my H3 and P1 pedals. I tend to look at 1 min, 5 min, and 20 power curves for each and if they are reasonable I live with it. I do not race so not a big deal. That said at the higher watts, say over 500 (which are fleeting), my difference is not quite that much…maybe 15-20 watts.

2018 model