Sum error Excel 2016 (Insider) Windows 10 Pro x64 (1809)

SergeiBaklan 

I think what's happening here is that I'm trying to execute a new set of commands from within the Spill of the Array commands and it's getting confused.

Below are the two formulas, the first that works most of the time and the second that produces a blank cell ("") as its result.

Works: {=IF(COUNTA(UNIQUE(Transactions!Expense_Center))+2=ROW(),"TOTALS",SORT(UNIQUE(Transactions!Expense_Center)))}

Doesn’t Work: {=IF(COUNTA(UNIQUE(Transactions!Expense_Center))+2=ROW(),"TOTALS",SORT(UNIQUE(Transactions!Expense_Center)))}

Both are running against a 1 x 300 array on another (Transactions) sheet. 

What I get, from the second, non-working, formula is that in the final step, as it should fill the cell with "TOTALS" is a blank cell from the Spill of the UNIQUE function. Prior to this, there was always a single entry of 0 (zero) that represented the blank values in Transactions!Expense_Center. The above formula looked at that, compared the 0 (zero) to the null ("") and found a true condition which caused the cell to be loaded with "TOTALS".

Now though seems to no longer work.

As far as I know, I've had no Office updates and other than the messed up update to 1809 no O/S updates that should affect this.

ANY help here I'd love it. I have tried separating the formula into different steps but haven't had success there yet.

Thanks for looking,

TheOldPuterMan

John