My Windows box reports “not a directory” too. On that machine it is because the constants are set to the old ‘Roaming’ path, not the actual new ‘Local’ folder.
Could there be a mistake in the routine that creates (or leverages the pre XDG path for upgrades) the Gramps User Directory in Windows? Where it decides the opposite (old) path when it should use the new path? The paths immediately below have a valid 'Local` in their breadcrumbs.
The LIB_PATH
also claims that it is not a directory. But it IS showing Local
. Maybe it wasn’t created?