I tried :
- waiting days,
- restarting,
- deleting the developer account inpreferences,
- submitting archives from a connected device,
- submittingarchives from a iOS generic device.
Nothing worked.
I needed to:
- create an archive (it was from a connected device),
- in the organiser window select the export button (on the right hand side underneath the "Upload to App Store" button.
- Select that the export is for app store distribution.
- Wait.
- Take a note of the location the .ipa file is saved to.
- Go back to Xcode, then select the menu item Xcode > Open Developer Tool > Application Loader.
- Select Deliver Your App, and select choose.
- Navigate to your .ipa file noted above.
- Select next, wait, next, check for any error message, send.
Hope this helps someone.