David Duarte posted a reply to a thread on this subject at AUGI stating that the Worksharing Monitor tool (available via Autodesk Subscription) does not detect activity with files that contain an additional period (.) in the file name.
For example: MyAwesomeProject.NoReally.central.rvt
I imagine this is because Revit uses an extra period (.) followed by four numerical values to define backup files.
For example: MyAwesomeProject.0003.rvt
Odd since that only really applies to stand-alone projects. Regardless this little bit of information may help resolve what otherwise seemed a bit mysterious.