Bulk Upgrade - Revit with Subfolders

Hello ,

I have a simple bulk upgrade script, however the “Include Subdirectories” of the FileSystem.GetDirectoryContents node, is returning “empty list”. The script will run what is in the main directory, but nothing in the subfolders. Is there a way to direct it to find the files in the subdirectories too?

We have a main Revit file in the main directory, and Revit Linked files in the sub-directories.

Thanks in advance, A