I’ve downloaded it into Excel 2010 (yes, old; works for me tho) and it complains that there some formulas it had to “recover”. Can’t yet say which ones and how big is the damage. Then again, maybe it works fine for newer Excels.
Huh, I see now. The formulas for customer number got converted into just numbers. I.e. I have changed the number of customers in month 1 to 0, but month 2 still got 11 - because 11 is what Excel has got.
This is because for Excel the formula should contain the precision: