For me, it works fine.
I have the following Groupy2 settings:
General > Integrate the tabs; > Show all
Tab appearance > Always visible
Grouping settings > Replace File Explorer & Windows Notepad tabs; Explorer enhancement settings > New Explorer tabs should open in the same folder
And the following Notepad settings:
Opening files > Open in a new window
When Notepad starts > Start new session and discard unsaved changes.
Hope this helps.