Cant change mac addr on 19.07.0 rc2

I cant change mac addr of any dhcp interface via
option macaddr 'XX:XX:XX:XX:XX:XX'
in the "config wifi-iface" section of /etc/config/wireless
:confused: only happ on openwrt v19, v18 seems works

It work with uci command via ssh
Ifconfig interface_name hw ether xx:xx:xx:xx:xx:xx
But is not a constant change