We tried with Mikrotik versions from 5.20 to 6.18, and nothing.
No matter what is in country or frequency mode field on Mikrotik, AirGrid XW 5.5.9 with CTest as country wont connect.
I tried what you suggested, putting superchan and US as country, but nothing, and yet, when I scan from AG, I see my AP.
Also tried putting LOCK TO AP MAC - no luck at all.
And, look at this:
AP - AirGrid XM 5.5.6
AirMax is disabled.
Station - AirGrid XW 5.5.9 crcfixed
As you can see, I see it in site survey:
And I cant connect to it, but, if I fix scan list to channel 5300, it connects:
But this thing with scan list works only with UBNT devices, does not work with Mikrotik :(
Regards from Serbia!