Hello Jim,
You can run the ProGet service in interactive mode to see its logs:
Stop the ProGet service.
In Command Prompt or PowerShell, run .\ProGet.Service.exe run from C:\Program Files\ProGet\Service (or wherever you installed ProGet if you didn't use the default location).
It will run the drop path monitor every 60 seconds by default. The message for the drop path monitor starting is Executing DropPathMonitorExecuter....
You can edit Service.DropPathMonitorExecuterThrottle in /administration/advanced-settings to less than 60 seconds if waiting gets too annoying.
Immediately after the drop path monitor runs, there should be a message that says Scanning for packages in f:\dsc\droppath. This will be followed by Found f:\dsc\droppath\file.ext any packages it finds.
In order to be found, the package files must end in the expected extension:
.tgz for npm feeds
.nupkg for NuGet feeds
.gem for Ruby Gems feeds
.upack for Universal feeds
.vsix for VSIX feeds
If an error occurs while trying to add a package from the drop path, it will appear on a line shortly after the Found f:\dsc\droppath\file.ext line, starting with Error installing package:.