Purge does not purge released artifacts

I am running into a problem when running mvn dependency:purge-local-repository in that it does not remove any local artifacts for a large multi-module project.
I run it from the parent directory and it reports the following for all my sub modules

[INFO] Nothing to do for project: .......

I expect the goal to examine all my dependencies, including transitive dependencies, and remove them from the local repository.