License Optimizer for Jira Servicemanagement
Assigning Issues to Unlicensed Users
The following might not always be required, so please verify if you can assign users managed by License Optimizer first.
When using License Optimizer for JSM, please ensure that the “original” Jira JSM group under Allowed Users Group from the License Optimizer for JSM configuration ...

... has been added as a role of type Service Desk Team in your JSM projects:

Otherwise, you can't assign issues to currently unlicensed users. You can also use any other group with the "Browse Project" permission assigned for the project.
Auto-Assign Issues Based On Component Or Project Leads
Assigning issues automatically to users based on project or component settings doesn't work if these users currently don't have a license assigned due to their inactivity.
The option below enables License Optimizer to assign the issue to the right user. Same as Jira does by default, if there are multiple components assigned to an issue, the first component in alphabetical order is the one from which the assignee is derived.

Caveats
We won’t automatically assign a new issue if it has been assigned to someone else for any reason, such as custom automations or scripts.