Set-PnPFolderPermission : File Not Found

[wil16098]

I appear to be correctly connected to the following services as a Global Administrator:

Connect-SPOService -Url https://$clientOrg-admin.sharepoint.com
Connect-PnPOnline -Url https://$clientOrg.sharepoint.com/sites/Files -Interactive
Connect-AzureAD
Connect-MicrosoftTeams

Get-PnPContext appears to show I am connected to the "Files" communication site correctly:
Url : https://[tenantname].sharepoint.com/sites/files

I am attempting the following command:
Set-PnPFolderPermission -List "Advanced" -Identity "Training" -Group "Training Team" -AddRole "Edit"

I get a "File Not Found" error:

Set-PnPFolderPermission : File Not Found.
At line:1 char:1
+ Set-PnPFolderPermission -List Advanced -Identity "Training" -Group "T ...
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : InvalidOperation: (:) [Set-PnPFolderPermission], PSInvalidOperationException
    + FullyQualifiedErrorId : InvalidOperation,PnP.PowerShell.Commands.Files.SetFolderPermission

Get-PnPList appears to show the Advanced Document Library is present:

Title                 Id                                   Url                                  
-----                 --                                   ---                                  
Advanced              2764a050-2316-41f4-4388-7a132643bcd1 /sites/Files/Advanced

Get-PnPFolder -List "Advanced" #shows the folder "Training" and its subfolder are present:

Name                               Type   Items/Size Last Modified         
----                               ----   ---------- -------------         
Training                           Folder          1 12/20/2022 11:35:44 AM
Z - Training Admins                Folder          0 12/19/2022 11:26:40 AM

Get-PnPGroup does not list the MS Team "Training" (which does exist). This has me concerned but doesn't appear to match the error I am getting.

Id Title          LoginName     
-- -----          ---------     
5  Files Members  Files Members 
3  Files Owners   Files Owners  
4  Files Visitors Files Visitors

Any insights into this error and why I am getting this unexpected result appreciated. My Global Admin account is the primary owner of the Files site.