The HA feature of the ido-connection does not create a fully synced database on two nodes.
@dnsmichi explained this here: Implementing HA Master-Master setup - #8 by dnsmichi
I previously had this “illusion”, but it was just wishful thinking^^
So two have two synced databses you would need to have some form of replication.
A change to the ido config will need a reload of icinga2.