Upload of (large) snapshot fails when trying to restore?

I have an 800MB snapshot which I would like to restore on a fresh install.
On the onboarding screen I select “Alternatively you can restore from a previous snapshot”,
the “Upload snapshot” popup appears, and my OS file selector.
I select the tar file, the uploading starts, and I see the spinner.
This disappears after a few minutes and I see the “Upload snapshot” again, where can I click on the file selector again.
I don’t see an error message (e.g. file too large).


I am having a similar problem trying to restore a pi4 backup to my new HA blue, I select the backup .tar file (758meg) , and after 5 or 6 seconds of the spinning blue circle , its back to the upload snapshot file selection box.
Any help would be appreciated.