What I am experiencing is that a Mikrotik device will not update from a Mikrotik device. I have a hEX that is connected to the ISP as my primary router and two hAP ax3s connected to the hEX. They are network neighbors; they are on the same VLAN. The hEX has no problem receiving NTP updates from us.pool.ntp.org, and devices such as my Windows laptop have no problem getting NTP updates from the hEX. But neither hAP can get NTP updates from the hEX. They always remain in the waiting state when configured to receive NTP updates from the hEX. But when I configure them to get NTP updates from us.pool.ntp.org, there is no problem; they change to synchronized state in less than a minute. The hEX is the path to the ISP, so the NTP updates to the hAPs are passing through it to get to the hAPs. So, my conclusion is that Mikrotik NTP cannot talk to Mikrotik NTP.
-Mark