In rare occasions we'll get a report of a 'Loading Targets ...' message that sits indefinitely. It's not necessarily an error, but a status indicator that will ultimately sit there until targets can be loaded. If targets can't be loaded, the message just remains. There are a couple of reasons the page may have trouble loading targets.
This error often occurs as the result of "link-hacking". In other words, grabbing a previous action's link and appending the new action's key to the end of it. If the actions are of different styles (ie. action3 versus action4) then this error will occur.
It can also occur when launching the action from an outdated Action Listing.
The best way to ensure that you're loading the appropriate URL for your action is to access the action in Salsa, and use the 'Show Publishing Tools' section to launch the action:
We've also seen rare scenarios where a browser simply won't clear its session cache (stored cookie information), causing this problem. To test whether or not this is the case you're experiencing, you can simply launch an "Incognito / Private" window in that same browser. Then, navigate to the same URL. If targets load fine in an "Incognito / Private" window, then it's a session cookie problem. Unfortunately, we don't have complete control over how the browser retains cookies. If closing / reopening the browser doesn't resolve the problem, then clearing the browser's cookies will resolve it. In some browsers, you can even choose to clear cookies for only a specific site (instead of clearing them all).