Chrome is my preferred web browser but when it comes to sending emails with attachments I 'm forced to use other web browsers such as Opera / Safari which do not suffer this issue.
It so annoying having spent half an hour etc written a massive tome to find you have to start all over again.
I suggest flagging this up with both parties since it has to be an issue with the coding of either the browser or the web mail GUI.
Every Frame a Rembrandt for a lot less Monet