IP/Cloud on a router with multiple channels

Situation:
There is mikrotik with two channels to the two ISP. The main channel ether1 with a static IP-address. Reserved channel is pppoe-out1 via ether2. Reserved channel has dynamic IP. We are trying to use IP-cloud functionality to know the current IP on the backup channel by the registered name. By using IP/Firewall/Mangle output chain I made a rule for traffic to UDP/15252 and the traffic sent through a backup channel. Everything works as it should until change of the IP-address on the pppoe interface. The address in the DDNS is not updated. If you say the Force Update it will updates correctly. The documentation for the IP/Cloud says:
“Router checks for outgoing IP address change: every 60 seconds”
It is clear that router watching outgoing IP in some way other than UDP/15252 and does not see the changes. How the router looks for IP address change? According to the routing table? According to the table of interfaces and their IP-addresses? Or some kind of traffic? If the latter option, I can make another Mangle and fix it. If the first option, only forced through a script on schedule. If the second, then rpouter has error in software.
How to configure DDNS for my case?
RouterOS version 6.33.3 on RB951Ui-2HnD. I know that is not the last software, but I doubt that update help me.

Just add to scheduler command to force update to some time interval I usually add 3 or 5 minutes.