Slack notifications don't ever occur?

I have successfully linked Monday with Slack (and re-authenticated for good measure at least a dozen times), but no one on my team gets notifications on Slack when they are assigned a task or when they are mentioned in a Monday comment. No one in support seems to understand what I’m asking. Does anyone have insight into why this is happening and any solutions? If this doesn’t work, it’ll cost me thousands that I’ll have to spend to leave Monday.

Strangely I know for a fact it should be working because recipes I created to do other functionality like alert the management team when a status is changed on a task DOES deliver a notification. But this core functionality of notifications for assigned tasks and mentions never delivers a notification.