Hey Josh - I think we've now isolated the issue to email programs specifically (as opposed to sending from smart campaigns). I will keep you posted when they can identify the issue.
Aubrey, please keep us posted - as you work with Support - on how this progresses toward resolution. Thanks for surfacing here.
Turns out we had hidden dynamic content in the email from what we cloned. No bug after all. Thanks for the help everyone!
.png)