[Resolved] Translation refuses to complete

Background of the issue:
I was trying to complete a translation using the WPML plugin. I clicked the Complete Translation button, but the expected behavior did not occur.

Symptoms:
When I hit the Complete Translation button, instead of changing to a pen icon, it turned into a gear icon, indicating that the translation is not complete.

Questions:
Why does the gear icon appear instead of the pen icon when I click the Complete Translation button?
How can I ensure that the translation completes successfully and shows the pen icon?