You can check whether a turnaround report was sent on the AGOA FIDS page: agoa.tarmactechnologies.com/fids. It shows, for each turnaround, whether the report has been sent.
This isn't available in the AGOA Mobile app for now, but you can open the FIDS page in your phone's web browser.
The report was sent, but someone didn't receive it
Check that their email address is in the report's recipient list. See Who receives the AGOA reports, and how do I change the recipients?
If you need to send it again, see Can I send my flight report again?
If the report wasn't sent, see What should I do if I cannot send my turnaround report?