[flavmartins]

It's especially bad if you're on mobile and in an area that might have spotty reception.

You post a message, it looks good, you move on.

Then later on you come back to it and it was never sent.

[dimtion]

The new Slack on mobile is absolutely unusable. There are no way to know if the interface is up to date, when was the last update or to force an update.

The only way I found to know that your message has been received is to have an ack from your interlocutor.

[ghostpepper]

My personal conspiracy theory is that Slack likes the way users "engage" with the mobile app when indicator badges don't clear right away. Often you will open the app because you see the badge, only to realize you've already read the message and the badge just hasn't cleared. They're hoping that you will then click something unrelated in the app, thus increasing "engagement".