Searching using NH, AC, BA
BA CAPTCHA popup occurs, I click through to the background Chrome instance used for search, and it opens to the middle tab (AC); I would think this should resolve to the BA tab for ease of use.
The problem is that the AC page sometimes needs to get focus for it to work and so when a new page loads on the AC page, it will get focus. So what happened is you clicked the notification and it took you to the BA page but then AC loaded another page and got focus.
This is also true for BA, QF and SQ. If you were searching just NH & BA, I believe it would work.