I'm not sure if this is a spec issue or a Relay issue, but I was able to reproduce this in Relay quite readily.
So if you correct the contents of a message (edit an event), Relay puts * the edited text (note the asterisk) in body and puts * in the formatted_body. Client's like alphapapa\ement.el will choose to use the formatted_body over body when it exists. Which happens to hide the entire contents of the edited message.

I'm not sure if this is a spec issue or a Relay issue, but I was able to reproduce this in Relay quite readily.
So if you correct the contents of a message (edit an event), Relay puts
* the edited text(note the asterisk) inbodyand puts*in theformatted_body. Client's like alphapapa\ement.el will choose to use the formatted_body over body when it exists. Which happens to hide the entire contents of the edited message.