I suggest sshing to one of your Unifi APs and verifying. My APs are running firmware version bz.6.5.28 released 3 months ago. It is based upon OpenWRT 17.01.6 according to the /etc/openwrt_release file on the AP.

Below are the complete contents of the file:

DISTRIB_ID='LEDE' DISTRIB_RELEASE='17.01.6' DISTRIB_REVISION='r3979-2252731af4' DISTRIB_CODENAME='reboot' DISTRIB_TARGET='ar71xx/ubnt' DISTRIB_ARCH='mips_24kc' DISTRIB_DESCRIPTION='LEDE Reboot 17.01.6 r3979-2252731af4' DISTRIB_TAINTS='no-all mklibs busybox'