'Formula 1' words appear in the pivot table!
 

Hi, when I use 'Group Selection' inside a pivot table, the words 'formula 1'
suddenly appear inside the data I am trying to group. and then if I am trying
to group say 10 rows of data, it only highlights 9 of them plus the row
beneath with the word 'formula 1' as the 10.. and the 10 data value appears
in the row below, but is excluded from the group. Any guidance please?
Thank you.