How to get formula for folder name to work in link to PDM?

In the link to PDM configuration, we chose to use check-in/out method.

We have an existing folder structure that Electrical is unable to use, so in order to avoid restructuring our entire PDM library, we must instead ensure that each time we check a project in, we first go to PDM and modify the link settings.  We had all agreed that this was the only way to make it work so that was all fine...but now, in trying to set this up, we have nothing but problems...

Here's an example folder structure:

PDM Vault\Schematics\Electrical\300\020\300-020-010

So in Link to PDM settings, I specify the following:

Base Folder Path:  C:\PDM Vault

Subfolder for Projects:  Schematics\Electrical\300\020 (this would have to be modified each time a project is checked in since the folders vary)

Formula for Folder Name: PROJ_NAME  (which in this case would be 300-020-010)

However, with this setup, SW Electrical, instead of writing to the folder above, which does exist, instead creates a new folder:

PDM Vault\Schematics\Electrical\300\020\27

It seems to be completely ignoring anything I input for the "Formula for Folder Name" - I've changed this to several different things but nothing will get Electrical to write to the correct folder.

It creates a folder called "27" regardless of what I specify, or even if I leave it blank and put the full path into the "Subfolder for Projects" instead.

All I want is for SolidWorks Electrical to write my project files (Archive, Drawing, 3D, PDF and Reports folders) into the already existing project folders that are created automatically by PDM, without burying them in an unnecessary sub-folder.

How can this be accomplished?

SolidworksElectrical