Comment 2 for bug 1766230

It has happened sometimes that Slack Notifications do not work. This error arises for various reasons and some of them are: Notifications Manager has determined that Slack notifications are not important; Do Not Disturb mode is preventing the notifications from going through, New notification behavior is not working properly, Quiet Hours (Focus Assist) is delaying Slack notifications and many other possible reasons. No worries because here we have some methods to resolve this error.

1- Read all your pending messages:
i). Users can solve this issue by reading all pending Slack messages. This will also send the right signals to Windows 10 that would make it possible that you would receive more messages in the future. For further info click the following link https://appuals.com/fix-slack-notifications-not-working/ You can do it by opening your Slack app, tap on each new messages to read it.

ii). After that close Slack and reboot your system. In case Windows was formerly seeing Slack notifications as not significant, this action should have altered now. iii). At the end when the startup is complete, monitor Slack’s behavior and see if you start receiving notifications.

2- Reverting back to the previous notification behavior:
i). As initial tap step Windows key + R to start the Run dialog box and write this instruction slack://notReallyWindows10 and press enter.
ii). At the end reboot your system and see if you start receiving notifications or not.