SUM not working when referencing cells of formula output

I resolved this issue, which I had it recently. it occurred for me in two cases 1) if a cell with subtotal() function is referred in the sum() 2) if a sum() function with the domain/argument is defined includes the cell where sum() function is. I resolved them to correct the root causes, which 1) don't refer to a cell with subtotal correct the sum() is has a range that includes its own cell, which you may write a composite, e.g. summation of sum() functions that spans separate ranges.