While configuring the radio0 device, you can set a country (presumably the one you currently reside), which will in turn provide you with a list of available channels based on regulatory database entries in package/kernel/mac80211/files/regdb.txt. However, the country list itself it taken from iwinfo_lib.c, which does not correlate it's list with the regdb.txt file.
There is a very similar thread that explains this problem here:
The problem with the thread is that it only mentions it as GUI bug. While in reality, if a country does not have any regulatory information about it written up in regdb.txt, it will choose the previous country regulations. (This is also quite stealthy, as the country name will actually change to what you designate it to, so you are unlikely to think that something is amiss) This might prove somewhat problematic as the channel settings could be breaking some kind of regulations.
So my question is: Should the countries without any regulatory information be listed there in the first place? The fix for this would be quite simple - simply remove the entries in iwinfo_lib.c or patch the logic to select '00' world regulatory zone by default it there is no entry about it in regdb.txt.
Edit: Upon further thought, the second patch suggestion (to default to '00') would be a tad bit difficult to provide as you would likely have to iterate over the entire regdb file to check whether the country exists or not. It seems less ninja'y and stealthy to simply remove these countries: https://pastebin.com/M2qTQFT5 (though this patch was created on an older version of OpenWrt, so might need some tweaking)
Edit #2: Here is the post where I display the problem using a month old snapshot build (it is lower down in the thread, though for ease of reading I decided to put this here as well):