When SOI manager stopped publishing any alerts, there are some errors below you have found in SOI\tomcat\logs\soimgr-debug.log from SOI manager.
ERROR [ActiveMQ Transport: tcp:///xx.xxx.xxx.xxx:xxxx] cursors.AbstractStoreCursor.reset(112) - Failed to fill batch
java.lang.RuntimeException: java.io.IOException: Could not locate data file E:\Program Files (x86)\CA\SOI\tomcat\webapps\activemq-web\activemq-data\db-176.log
at org.apache.activemq.broker.region.cursors.AbstractStoreCursor.fillBatch(AbstractStoreCursor.java:265)
at org.apache.activemq.broker.region.cursors.AbstractStoreCursor.reset(AbstractStoreCursor.java:110)
at org.apache.activemq.broker.region.cursors.StoreDurableSubscriberCursor.reset(StoreDurableSubscriberCursor.java:240)
If you go to SOI\tomcat\webapps\activemq-web\activemq-data on SOI manager, you couldn't find this db-176.log file existing.
This problem can be temporarily fixed by cleaning up SOI\tomcat\webapps\activemq-web\activemq-data folder and restarting SOI services.
This is problem is caused by an issue in ActiveMQ 5.4.x. Below is the link to state this problem in Apache ActiveMQ.
URL: https://issues.apache.org/jira/browse/AMQ-3122
The problem has been fixed in the ActiveMQ 5.5.0 and any newer version than 5.5.0.
If you would like to resolve this problem permanently, please upgrade SOI to 4.2. SOI 4.2 comes with Apache ActiveMQ 5.14.4. Please find the following release note for SOI 4.2.
URL: https://docops.ca.com/ca-service-operations-insight/4-2/en/release-notes/ca-soi-r4-2-release-notes/system-requirements/software-support