Audio file disappear

I am facing a problem.
I uploaded a questionnaire on server 10 days ago with audios enabled.
everything was working fine and my audio files were of 6.5 Gb.
But suddenly 2 days ago the file size decreases from 6.5 Gb to 1.6 Mb that is surprised.

Is there any solution for this or one can explain the issue?

Please urgent .

Dear Babar,

thank you for reporting the issue.
This has been identified as a bug in our code.
The data is still stored on the server. The bug affects solely the export of binary data resulting in empty export.

Our team is working on producing an update that will fix this issue. This will be deployed as soon as it is ready.

We regret any inconvenience that this issue may have caused.

Sincerely, Sergiy Radyakin

Deployed version 19.07.4 should resolve this issue.