Slack has developed this bug where all of the text in your text box disappears and you think it’s lost but it’s actually in an invisible buffer. When you re-type your message it will also paste in the text from that buffer. Absolutely maddening and hard to reproduce. Cc @SlackHQ
Oh yikes. You're right, that's no good at all. That said, we don't believe we've had any other reports of this, so it's hard to investigate. If you haven't yet, would you mind writing in to feedback@slack.com so we can look into it? You can link this tweet thread.