JCMA doesn't allocate the 'Customer' role to the Internal customer

Issue Summary

We have seen issues where the 'Jira Service Management - Customer' role is not allocated to the Internal customer(with Atlassian account) post-migration from Datacenter/On-premises to cloud.

This is reproducible on Data Center: yes

Steps to Reproduce

1. Create a Jira Service Management (formerly Jira Service Desk) project
2. Create a customer account on DC/On-premises
3. In JCMA, check the domain of the customer as a Trusted Domain
4. Migrate the project by JCMA (either project by project/Migrate all data at once option)

Expected Results

'Jira Service Management - Customer' role is allocated to the Internal customer(with Atlassian account).

Actual Results

'Jira Service Management - Customer' role is not allocated to the Internal customer(with Atlassian account).

Workaround

Follow the steps on How to allocate the 'Jira Service Management - Customer' role in bulk?