Normally, Slack will be shut down in order to patch for macOS devices. It will not be shut down on Windows devices.
For any OS, if a call is in progress, Automox will not close Slack. In addition, there can be a discrepancy that when the call finishes, Automox will not recognize that the call has ended. In this case, it never shuts down, and therefore, never patches.
Solution: If a call was in progress during the scheduled patch time, the patch will be updated the next time the policy runs, as long as there is no call in progress. You can also decide to manually patch Slack.