Are you using gmail or some email client like outlook? I use gmail and didn’t see an issue attaching the file to email or downloading the file from the email… The only thing might be borkage from a desktop email client… or could be a bad extension… Can you try with all the extesions disabled (or in a private window)?
The object was to try it without any extensions and see if downloading works. You can also simulate that by using a new profile to test the downloading as well…