Open Radar

 
Summary:
I am using Wi-Fi connection at school. At the end of a lesson I just close the MacBook and I go home. At home I open MacBook, log in and OS X does not connect me to my home Wi-Fi althought it is saved in known AP. OS X cannot connect me because it cannot see this Wi-Fi on channels 12 and 13. My Wi-Fi is at channel 12, so OS X cannot se it.
But WHY? System report shows Country code: US. But WHY?
At "Language&Region" is preferred language just and only "Čeština" and Region is set to the "Czech republic". List sort order is set to "Czech". Data&Time -> Time Zone has got disabled automatically using current location and is set to the city "Brno - Česká republika." (my school is at the same city)

Steps to Reproduce:
1. close MacBookAir6,2
2. move it to another location
3. open MacBook and login
4. OS X is not able to see Wi-Fi on 12. and 13. channel 

Expected Results:
I should be able to see and connect to Wi-Fi on channel 12 and 13.

Actual Results:
OS X cannot see Wi-Fi on channel 12 and 13.

Version:
10.11.4 (15E65)

Notes:
I have to turn Wi-Fi off at Network preferences of my Mac and then turn it on several times (ex. 6 times).

Configuration:
Problem occurs only when using OS X, when I am using Windows10 on the same device, everything is OK. The problem was with OS X 10.11.3 as well.