Cannot send document via email from LO 7.1.4.2 Flatpak

Hi,

I'm running LO 7.1.4.2 Flatpak edition and I am unable to send the
current document via email. When I try the email dialogue comes up, but
there is no document attached. When I click on send, the recipient gets
an email with no attachment.

My email client is Evolution version 3.36.5-0ubuntu1

All running on Ubuntu 20.04.2 LTS and Gnome 3.36.8.
I'm not sure if this is an LO bug, consequence of using Flatpak,
Evolution problem and a configuration issue!

Any ideas on where the issue lies and how I might go about fixing it?

Many thanks.

Regards,
Tony.