What does the "Vertex association not found" [WARN] message in the IntroscopeEnterpriseManager.log mean?

Users started to see the following [WARN] message in the IntroscopeEnterpriseManager.log, after switching the data source for Team Center:

[WARN] [AppMapAsyncExecutor-7] [Manager.AppMap] Vertex association not found: 515

For example, the following changes were made in the IntroscopeEnerpriseManager.properties file:

CHANGE:
introscope.apm.appmap.legacy.data.source=false

TO:
introscope.apm.appmap.legacy.data.source=true

What does this [WARN] message means, and what is the impact of it?

The [WARN] message represents that an item on the AppMap that was expected is not available. This can be resulted from changing the legacy datasource setting. This legacy datasource setting changes the way items are added to the TeamCenter. The messages are unobtrusive and harmless. It can be safely ignored.

Related KB:

Attempt to write vertex but there is already such a record written