Opening DuoBot's translation removes comment
When I've finished writing my translation in immersion, I often look at Duobot's suggestion to double-check. If I've attached a comment, opening the suggested translation will remove that.
Seems like a somewhat unobvious bug. It doesn't appear to happen when you view previous translations (i.e. you're not the first person to offer a translation).
Also, the improvements to comments that have been made over the past couple of months are awesome. And so is the Discussion.