This issue can have the following causes:
<SmartsBaseDir>./dmctl -s <APM Domain Name> invoke <class>::<instance> remove
IMPORTANT! The device needs to be removed from all the Smarts domains.
./manage-modules.sh service stop collector-manager Default
APG administration > Modules > Management of Database Metrics
./manage-modules.sh service start collector-manager Default
<APGbase>/bin/apg-tomcat-default restart