Root cause: This is because of QLS Agent version is not up-to-date.
Solution:
Step 1 - Kindly refer this KB ' How to Update QLS version' for update QLS version.
Step 2 - After update QLS version, go to QLS Agent > License.
Step 3 - Click Licenses > Click Transfer Licenses In from Cloud.
Step 4 - Wait for Synchorizing Licenses.
Step 5 - Licenses updated.
Now can login QnE Optimum.
Thanks.