This is a known issue and is identified in the Field Bulletin found -here- . Look for the Field Bulletin called Avoiding 100 Series access points power amplifier failure - Tuesday, November 19, 2013".
Beginning with AOS 6.1.3.6 and 6.2 and higher you can no longer do "hybrid spectrum" on the 5GHz radio on the AP-104 / 105. Other AP models are not affected.
The -104 / 105 do support Spectrum in 5GHz but in Dedicated mode only. Both modes are supported on the 2.4GHz radio.