ROS do not reply SOA DNS record by default, even if the SOA record has been obtained from the upstream DNS server and has been displayed in the ROS DNS cache.
For example: Cloudflare tunnel cannot be started because the returned (argotunnel.com) domain record does not contain an SOA record.
This issue exists in both 7.11.2 and 7.12beta9
I have seen some discussion on the 7.7rc post.
http://forum.mikrotik.com/t/v7-7rc-is-released/162872/230