Retrieving Outlook folder using GetNamespace causing Runtime error

I have a macro that moves the currently selected email to a folder based on a keyword in the subject line matching a folder name. The macro extracts the keyword and then recursively descends the Outlook folder tree beginning with a "startFolder" which I manually define. The macro has been running just fine for months. Then the other day it stopped working.

    Dim OutApp As Outlook.Application
    Set OutApp = New Outlook.Application
    
    Dim Namespace As Outlook.Namespace
    Set Namespace = OutApp.GetNamespace("MAPI")
    
    Dim Folder, startFolder, SubFolder, UserFolder As Outlook.MAPIFolder
            
    Set startFolder = Namespace.Folders("G Suite - xxxxx.com").Folders("Mail Folders").Folders("XXXXX").Folders("Projects")

....

Now the Set statement results in a runtime error:
Runtime error ' -2147221233 (8004010f)':
The attempted operation failed. An object could not be found.

Again, this was working just fine, no changes. I exported the module and reimported just in case it was corrupted (that's solved other problems), but that did not work.