Hi Igor,
I found the issue, the reason why UFW and the armbian-config AP doesn't work well when rules are added is because to allow forwarding the DEFAULT_FORWARD_POLICY must be set to ACCEPT in /etc/ufw/sysctl.conf which allows ALL traffic to pass through without being affected by the firewall.
I think for the armbian-config AP mode to work with UFW, bridging might be needed.
Thanks,
Maheen