I am using Windows 8. For some reason I haven't been receiving the slack notifications on my desktop. When I searched online for help, I got suggestions to turn off the focus assist, but it was of no help to me, as I didn't find anything like focus assist on my Windows 8 desktop. Slack notifications settings window
I tried to enable notification sounds from the notifications and action center, but there was no option to enable the notifications for slack, all it was showing was windows apps only.
Yes, you need to turn off the focus assist, then you will get a slack notification. The below steps are for windows 10 but it may work for you too:
