Hello, Gentleman

I have setup with rb3011 and 3 Cap AC's. 3011 serves as capsman controller, and fully controls ac's.
My question is next, when i set tx power level to some dBm, 2 ac's are setting it correctly, and 3rd setting levels below i assign. For 5ghz it sets for 3 dBm less, for 2.4 it sets 2 dBm less.
It doesn't matter how much i want, if i set to 15 dBm, on ac i see 12/13. If i set 3dBm, on ac i see 1. If i set 20, i'll get 17/18 :)
All settings seems to be the same (i've checked step by step), even if forget about fact that all settings are assigned through capsman. Please suggest something :)
All devices are running 6.47.8
Wireless page on 2 ac's (one "good", one "bad") at the same time.