The most common issue is a user is behind a VPN / firewall or there are IT security policies preventing uploads to cloud storage (the first step to transcribe your file). Please check with your IT team and disable any VPN/firewall.
Other reasons why uploads may be failing:
Your file is corrupt. While it seemingly may play on your computer, there may be corrupt bits. We see this often with Zoom / video conference calling recordings where the end of the recording wasn't "closed" per optimal audio/video standards.
Your file is too large. Simon Says supports 5GB uploads via the web. Use a cloud drive or use the Mac app.
The file you are uploading is not a supported audio/video file format/codec.
You are trying to upload a file without an extension.
You are uploading a file that is not an audio or video file.