I am currently having this issue. Windows 10 Home version 10.0.19042 and Groupy version 1.5. The issue appears to be that Groupy creates the groups above the title bar and doesn't move or resize the window such that if I have a window that is already snapped to the top of the screen and I have Groupy group windows then it will put the group tabs above the bounds of the display, above where the title bar of the existing window is and I cannot access the tabs with my mouse. This does not happen when I group the windows with Groupy first and then snap the windows to a specified zone in FancyZones as the tabs appear very top, but are on screen now and accessible with my mouse.
I believe this is known issue. I believe the Dev is looking into it. You can use the "Combine if possible" mode to help on this issue.

Thank you,
Basj,
Stardock Community Assistant