"Execute Now" button doesn't seem to work

[asachs01]

Expected Behavior

When pressing the 'execute now' button in the UI, I should observe events showing up in the UI immediately.

Current Behavior

When pressing the button in the UI, events don't show up, and may not show up for some amount of time. The same behavior is observed when using the API.

More context in the first part of https://secure.helpscout.net/conversation/1179647725/21386?folderId=1567755

[portertech]

There are a number of actions that need to take place after the "execute now" button is pressed. For example, the check request needs to be created and published to the appropriate agent sessions, the agents receive the requests, they independently execute the checks (can take a while), publish events, and one or more backends needs to process and store the events.

We need to better set expectations. Tip, message, wording, graphic. For example, "Your check execution request has been received. Doing work."