App Store Update Stuck on 'Pending' - MacBook Pro

My notifications for the App Store show that "Slack" requires an update. However, this process seems to be stuck in a 'pending' state.

I have restarted the laptop on numerous occasions and even left the laptop all night long to see if it were just being really slow to no avail.

I can't recall if I deleted the app and reinstalled it as this problem has been going on for some while now, but it would be something that I would try before asking for help so I assume I have.

What is there left that I can try to resolve this rather frustrating issue?