I'm using the image Armbian_5.38_Orangepizero_Debian_stretch_next_4.14.14.7z. My NetworkManager version is 1.6.2-3.
Certain NetworkManager options like
wifi.scan-rand-mac-address=yes
or
wifi.cloned-mac-address=random
for NetworkManager results in not being able to connect to a wireless Access Point anymore via nmtui.
On the other hand, manually spoofing the MAC address via ip, ifconfig and macchanger and using nmtui afterwards works in all three cases.