K9 silently discards inline edits

Expected behavior

K9 should allow in-line edits to be saved as draft normally like non-in-line edited emails, without deleting the in-line edits when you send it.

Actual behavior

When replying to an email, K9 allows me to edit inline by clicking on the pencil icon. Everything seems to work normally during he edit, including saving to drafts so you can come back later and finishing the email. But if you've saved the in-line edits as a draft and come back to it, then when you send the email, all the edits are omitted from the sent email, and since the mail was sent, it is removed from the drafts folder as well. All that editing time lost!

Steps to reproduce

1. Open a reply to an email
2. Click the pencil icon to edit in-line, i.e. so you can respond point-by-point to the person's original email.
3. Save that as a draft and come back to it later. When you ultimately send it, all the inline edits and the original quoted email are omitted from what is sent.

Environment

K-9 Mail version:
5.6

Android version:
9
Account type (IMAP, POP3, WebDAV/Exchange):
IMAP

Please take some time to retrieve logs and attach them here:

Reproduce the issue by editing a reply inline, saving it as a draft, reopening it, and sending it on the reported Android/IMAP setup. Trace the draft-loading and send flow to determine where the inline edits and quoted message are lost; done means the reopened draft sends with both preserved.