We currently have a pilot program running for our move to Lightning Experience, and I have had this issue come up a few times.
When the HTML version of an email contains bloating, the case feed will show a blank email, with no content. You have to go to the email itself in the related list to see the plain text version of the email. In the Classic Service Console, it was smart enough to realise that there was bloat, and show the plain text version in the case feed. I would like the same experience in the Lightning Service Console.
I have just been told by Salesforce Support that this is a feature request and I should raise an idea, so I have raised an idea for others to vote on, as I'm sure I'm not the only one experiencing this.
https://success.salesforce.com/ideaView?id=0873A000000CVA1QAO
Hi Vincent, bloating is where the XML or header is exceeding the character limit as it contains essentially a lot of unnecessary characters.
Support ticket is 20080751
