Symptoms
Focus method doesn't work when called from 'When a Tab] is Clicked' rule.
Diagnoses
The 'Clicked' method appears to run actions before the tab element gains focus from being clicked on, so any focus that has been granted will be stolen by the tab.
Resolution
Using the 'When the hTab] is Selected' rule works as intended, firing off actions after the tab has gained focus, thus allowing elements on the tab's view to successfully take focus.