Error when checking permissions in Role Permission Manager

Hi ,

I’m encountering the following error when trying to check permissions for Purchase Manager using the Role Permission Manager in V12.23.0

DocType Supplier Type not found
The resource you are looking for is not available

The console shows the following:

POST https://mydomain.org/api/method/frappe.core.page.permission_manager.permission_manager.get_permissions 404 (NOT FOUND)

Any ideas how to get around this pls ?

Kind regards,