Granting 'Browse Projects', 'Assign issues', 'Schedule issues', 'Create issues', 'Add comments' or 'Create attachments' permissions to the 'Service Desk Customers' role will make signup unavailable

Issue Summary

Granting the 'Browse Projects or Assign issues or Schedule issues or Add comments' permissions to the 'Service Desk Customers' role in a project with login-free portal permissions won't allow customers that don't have accounts to create tickets via e-mail or the portal.

Steps to Reproduce

1. Configure the Global and Project Customer Permissions to allow anyone to create their own accounts and to send requests without logging in
2. Go to your Project settings > Permissions > Actions > Edit permissions and add the role 'Service Desk Customers' to the 'Browse Projects' permission
3. Send an email to your project's email account from an address that is not associated with an account yet OR go to the portal without being logged in, create a ticket and inform an e-mail address (not associated with any account) in the "Email confirmation to" field.

Expected Results

In both cases, Jira will create a ticket and a new customer account.

Actual Results

Ticket and customer account are not created and the error Signup is not currently available will appear in the portal / email logs.

Workaround

Remove the 'Service Desk Customers' role from the 'Browse Projects or Assign Issues or Schedule Issues or Add comments' permissions.

Notes

This can also happen when the Service project customer - portal access is missing create issue and browse project permission, which prevents the customer from creating the issue from the portal, though the error message is misleading that the sign-up is not available.