Signals Notebook: User is unable to add a location to Inventory

In Signals Notebook, when a user tries to add a location to inventory, they get an error.
Inventory is properly activated, and user roles have been assigned.
How can I solve this issue?

A statement needs to be added to the SNB Security Policy granting access to Inventory for users.

Log in as Admin user, go to System Configuration - Security Policy and add following text (if the text is already present, remove “#” commenting symbols at the start of each string to make statement active):

##Grants access to Inventory
Rule "Location Write"
IF
user group in "All users" and
Resource type equal "location"
THEN
grant "entity.write"

Note: to create more secure rules based on different attributes, please see the System Configuration Guide and look under Inventory – Attribute Security Policy Configuration