G'Day Mates -
I'm having troubles mentioning regular customer on JSD, this is my scenario:
JSD Version: 4.5.1
Jira Software: 8.5.1
User is a regular customer, no permissions, no groups added, the user is not even on the Users and role section:

Customer is part of an organization on the project:

Project Customer Permissions:

Project Permissions:


Global Permissions:
When User doesn’t have an interaction with the Issue, it cannot be mentioned:

If the user has interacted on the issue, it can be mentioned:

Why this is happening? Is this a regular behavior?