[Chiuso] Empty translations queue

Background of the issue:
I am trying to resolve an issue on our staging site where translations aren't appearing in the translations queue, even though a corresponding job is listed on the 'Translation Jobs' page. I have ensured that the testing user is marked as a translator with the correct languages added and have tried several reset functionalities from the 'Troubleshooting' page inside the plugin. A direct link to the ATE via translator's email notifications still works. In a local development environment, the translation queue works as expected.

Symptoms:
Translations aren't appearing in the translations queue on the staging site, despite being listed on the 'Translation Jobs' page.

Questions:
Why aren't translations appearing in the translations queue on the staging site?
What steps can I take to resolve this issue?