Resolving Incomplete Hook Clicks in MixPanel Experiment Tracking

We're running an experiment in MixPanel, and we use the Experiment Started event. The experiment should include all users who open the site and see the specific test text, and we're looking for hook clicks on the button containing the test. The problem is that not all hook clicks show as part of the test. Why is that, and how can we resolve it so that all hook clicks are a part of the test?