Windows 10.
Using "Place Tabs above", then Show a Groupy bar when the mouse hovers over the top of a title bar for ungrouped windows is ON, How should taskbar buttons for Hrouped windows appear, is set to Show All.
Using Rounded Tabs, Background Bar to the tabs is ON, Tabs is set to Always Visible.
[Checked] Explorer enhancement settings: New Explorer tabs should open in the same folder.

If I click on the [+] button, it opens a NEW window. If I leave that window alone, and click on the [+] button again on the original explorer window, it will make a new tab correctly on that window next to the tab, and so-forth. I can close the newly opened window it made.

I am going to try setting it to Grouping rules --> [Checked] Automatically group identical windows together unless they are already in another Group

and see if that helps at all, as it was not checked before.

BTW, the only thing I am using Groupy for, is to only have the Grouping rules set for "Block / sloow applications" for "explorer" [Checked] Only allow specified applications to be in a Group. I just want the Windows Explorer to use this benefit, not every program I use.