Strange freq. usage values in 5Ghz band on WAP ac

Hi.
I have a strange freq. usage data in 5GHz band from my RouterBOARD wAP G-5HacT2HnD.
Please take a look at Pic1.jpg.
The usage values is almost stable. Only sometimes they decrease at half for 1-2 seconds.

Two different CAP ac located nearly WAP ac doesn’t show any similir in “Freq.usage” page.
CAP ac - brand new, just for freq. usage control test.

If i disable “TX chain 1” and “TX chain 2” on WAP ac - that usage on 5240, 5320, 5680 MHz disappears.

WAP AC:
ROS version is 6.44.1. Firmware: 6.44.1
2Ghz module is disabled.

Probably self-generation loop ?
Has my “WAP ac” device have malfunction in RF module ?
Pic1.jpg

Hello.
if i put WAp AC device in fully closed steel container with only small hole for ethernet cable - frequency usage values on 5240, 5320, 5680 appears the same.

Any ideas ?
Should I exchange device by garanty ?

Hi all.

The lastest ROS 6.46beta59 seems to solve the problem.
After update to 6.46beta59 I was able to enable all 3 chains, and described selfoscillations/usage at 5320/5680 Mhz disappeared.
Change log 6.46beta59 - contains the string about QCA9888 stability improvements, may be this is solves my issue.

I hope this help to someone.