Looks related to #4918, perhaps a duplicate.

Maybe, but if so, it manifests differently. In this case, focus lands in limbo and it doesn't usually occur. In the case of #4918, focus always lands on the first control in the dialog and you can reproduce it by simply switching to another window and back again; e.g. with alt+tab.

I doubt #4918 and this ticket are related in any way. The reported issue seems something far more general. Sometimes, when a large number of windows are open or there seems to be a significant processor overload, Alt+Tabbing around doesn't land inside the window and focus properly, just like the Log Viewer example cited here. I do not have any reliable STR or log to offer at the moment, but I shall try to provide the latter whenever next I experience this problem. CC @Brian1Gaff

I also experienced this problem. It seems to be accompanied by a Windows ding sound.

I cannot reproduce this issue in NVDA 2019.1.1 and have not seen this problem even in earlier versions. @geoff are you still having this issue?

@LeonarddeR are you still seeing this issue?

I am trying to reproduce this one with NVDA 2019.2 RC2 but without success. It works properly for me. @LeonarddeR are you still seeing this issue by chance?

We do not have any updates from the initial author since years. And I cannot reproduce this issue with NVDA 2019.3 Beta 2. Clsoing as abandoned and works for me. Please comment on it if you are still having this issue and we can reopen it. Thanks.