Huh, that's strange. I've never heard of this behavior before. I just tried it on a test instance and everything worked as expected (only the one initiative was disabled). The admin interface is not great, though. One thing that just tricked me, despite all my years of using this, was that after selecting another initiative from the drop-down, I still had to click the button to view that initiative. So, at first, I thought that the other initiatives had been disabled. It's an unlikely guess, but here's hoping...
Jason