Hi,
There seems to be a bug in the GroupCount procedure. It displays one row less than what is shown with Options.Grouping.ShowGroupCount.
I test it with V3.7.5.8, adding this code to the Button1Click on GroupDemo example:
TMSFMXGrid1.Options.Grouping.ShowGroupCount := true;
TMSFMXGrid1.GroupCount(4);
Regards,
Ricardo