@FGariepy471
Gantt chart usually works with calendar dates. If you prefer workdays only and interpret number of days in column G (if you din't change the template layout) as number of workdays, when in all formulas within calendar grid like
=IF(AND($C10="Goal",I$5>=$F10,I$5<=$F10+$G10-1),2,IF(AND($C10="Milestone",I$5>=$F10,I$5<=$F10+$G10-1),1,""))
you need to change $F10+$G10 (two places) on WORKDAY.INTL($F10,$G10,1).
It's enough in one cell and after that drag it down and to the right.
I didn't test, perhaps bit more adjustments will be needed.
