The APMSQL documentation is in the process of being enhanced. This knowledge document provides additional things to try for certain issues.
I am not getting all the expected results in APMSQL What should I do?
Customer environment was at APM 10.5.2 using Squirrel. But this could be for any APMSQL connection method and release.
SET TO DEBUG or TRACE in APMSqlServer.properties for helpful logging.