This glitch just came upon my widescreen setup also... Groupy suddenly does not play nice with MS PowerToys FancyZones anymore... when snapping a Groupy window into a FancyZone area, the tabs are invisible above the FanzyZones and can only be seen if painfully manually resizing the Groupy windows. The suggested workaround above (Combine if possible) does not resolve this. Please fix this glitch or Groupy will no longer be the amazing app it is for FancyZone users...
As mentioned this is known issue and has been logged internally by Support.
Stardock Community Assistant