All recent Intel cards use LAR (Location-Aware Regulatory) which means they ignore the region you have configured in software and the firmware won't transmit on any 5 GHz frequency unless it detects other access points already broadcasting on those frequencies, then it deduces what region you're in from that. So if you're in a quiet area with no other 5 GHz signals then the card will never transmit on 5 GHz.
This means if you want a 5 GHz access point, you can't do it with any recent Intel card, which probably explains why they are so cheap.
There's an open bug report for it but it requires persuading Intel to change the firmware so chances are slim this functionality will become available any time soon.
Old firmware versions had the ability to disable LAR, but this caused a firmware crash. Rather than fixing the crash and making the cards extremely desirable for soft-AP duty, Intel disabled the ability switch off LAR instead making the cards essentially useless.