SButtons, and I assume other clickable elements, currently require clicking “twice”, if the window/tab they are on is not in focus. This is more of an annoyance than anything. I changed the event when SButtons are created with from EButtonClickMethod::DownAndUp to EButtonClickMethod::MouseUp, and that alleviates the issue.
I would guess, that after focus is grabbed, then it is potentially possible to fire off the event “again” so the clicked object gets called, etc. I haven’t explored that option nor even looked to see if there was a different way to to do it.