Re: "I think this is a misunderstanding.
The mail will usually only contain the last of your messages."

= It has previously contained EVERYTHING. As far as I'm aware. Perhaps it was in EAP, then it got changed? I'd like to know.

What in the world is the point of creating a side conversation email to an external party etc. that does not then include the PREVIOUS messages?! Just the last one? It invalidates the whole point of an email chain.

Also, side conversation mails have no context, i. e. no content from the original ticket.

As has been pointed out above, you can add that. I have no issue with that, where you can pick and choose. This is helpful.

What is not helpful (in any context) is having an original side convo email to someone, several back and forths, and each time only the LAST message is sent.

When I add someone else to show the history of the email exchange, how am I meant to convey all that - when only the last message is shown? It used to do this naturally AFAIK.

There is no 'print ticket' option (save to pdf) either, as a worst case backup.