Our CDN providers have resolved this issue, no file uploads were lost in the upload process and will be in the media library.
Thanks for your patience and support :-)
We have had sporadic reports of audio uploads failing or taking longer than expected for large audio files.
Our technical experts have already started to investigate the issue and believe that this is something related to our CDN provider, StackPath. They are currently in contact with them and are working hard to resolve this issue as soon as possible.
Thank you for your patience and support.