Right, so i went into the Outlook of the Shared Mailbox that sent the emails, i can see they had a body but 4-10 MB of 5-8 attachments, and both a long chain of email. My admin UI attachment limit is 14MB and all file types were authorised.
I re-forwarded an email corresponding to the most recent of the 2 emails, reducing number of attachments, that worked quickly.