There does appear to be an issue also at my end with the Advanced find/results window. Both Outlook 2016 and 2019 (VirtualBox).
I do a search and have results showing. Then I can drag down the top window to hide the results and drag back to show them.
Dragging both down below the Taskbar and then back up only shows the Find window and not the results.
There appears to be no way to access the results.
The only way I have found to reset the windows is to use the New Search option (which loses the results you cannot see) and re-shows them on finding them.



I can drag up/down/left/right the window/results no problem, but once you go beyond the Taskbar, the results are gone.

Sorry I'm not able to offer any reaistic help to solve this.