Are you going to RMA? I will at least one unit - it is not cheap device to be this shitty!
I did some modifications to second unit because of low tolerance to USB capacitive load (http://forum.mikrotik.com/t/hap-ac-usb-modem-reboots-rb-bad-power-supply-design/96653/1 ). But fortunatelly the second one works at 40Mhz (but only on 1st channel)
Mikrotik really disappointed me - this fault, USB problem, LAN switch problem (as I read here in topic…)