When you change a location for an existing node with existing services from location Default to a Minion location, it seems the existing services are not scheduled to be monitored from the Minion location. The following example can be used to reproduce this issue:
Step 1. Create a node in location "Default", I've set an IP interface and added ICMP and SNMP. The IP address 172.16.1.20 is not reachable from the OpenNMS server and the expected behavior is to get a node down which happens correctly.
Step 2. Change the location from "Default" to "remote-network" where is a Minion which can reach 172.16.1.20.
After synchronizing the SSH service is discovered and goes UP immediately. The existing ICMP and SSH services don't get updated and stay down.
After restarting the OpenNMS core server the service scheduling works as expected.
To reproduce the steps see here: https://www.youtube.com/watch?v=ml4WQtLBcBk