In the Slack options, there is: `Show a badge on Mac on Slack's icon to indicate new activity` which is by default checked and `Bounce Slack's icon when receiving a notification` which is by default unchecked. Perhaps you want to flip both of these?
I also don't get notifications for general messages anywhere. There are 3 levels of notification settings, "Notify me about...": 1. "All new messages", 2. "Direct messages, mentions and keywords", 3. "Nothing". I use (2) everywhere.
I believe the badge options are Mac specific. I am on Ubuntu and talking with some Mac users just now they don't have the problem I have. On Ubuntu, there is no way (at least that I can tell), to disable the blue dot on new message. The only way I've been able to do it is with this:
I also don't get notifications for general messages anywhere. There are 3 levels of notification settings, "Notify me about...": 1. "All new messages", 2. "Direct messages, mentions and keywords", 3. "Nothing". I use (2) everywhere.