Answer
Text accepts mixed files; Image accepts images; Video accepts one image; Audio accepts none. Check only the device permission needed for the action, such as Photos, Camera or Microphone. Location permission is not needed for an ordinary file upload. Retry on a stable connection. Native mobile video sends can show processing or uploading before the message is delivered. A pending or failed upload is not proof that the attachment reached the chat or AI.
On iPhone builds containing the Photos video compatibility update, trimmed videos use their compatible stereo soundtrack when available. If an older build stalls before uploading a trimmed video, update the iPhone app and retry the attachment. Updating the website alone does not update an installed app.