I had a collection with number variables in it. Collection was just 1 set only. I am only concerned with the first 3 variables. 

I tried various ways to compute {current totals} = {current available}-{current timesheet}, but it error on 1-0. 

  =SUB(
    INDEX(Payroll_Use.Current_Available,1) , 
    INDEX(Payroll_Use.Current_Timesheet,1) 
    )
/******************* */

    =SUMIFS(INDEX(Payroll_Use.Current_Timesheet,1),"<>0",(
      INDEX(Payroll_Use.Current_Available,1) , 
      MINUS(INDEX(Payroll_Use.Current_Timesheet,1) ),
      INDEX(Payroll_Use.Current_Available,1) 
      )
/******************* */
      =IF(INDEX(Payroll_Use.Current_Timesheet,1) <> 0,
      SUB(
          INDEX(Payroll_Use.Current_Available,1) , 
          INDEX(Payroll_Use.Current_Timesheet,1) 
          ),
      INDEX(Payroll_Use.Current_Available,1)
      )
/******************* */
=IF(INDEX(Payroll_Use.Current_Timesheet,1) = 0,
  
  INDEX(Payroll_Use.Current_Available,1),
  SUB(
    INDEX(Payroll_Use.Current_Available,1) , 
    INDEX(Payroll_Use.Current_Timesheet,1) 
    )
  )

In the end I had to move the variables out of the collection and then the formulas worked just fine. 

Anyone else having issues with formulas inside collections?