Sum Measure Grand Total in Visual is Blank

Good morning, All.

I have a few simple measures that seems to give me the correct numbers but my grand total is showing as blank. I can't for the life of me understand why my total isn't showing. To explain, I am summing up a field called Difference and doing a comparison just to see if the previous quarter's numbers matches the current quarter's numbers.

My base measure is a typical sum: 

Total Difference = SUM('Table'[Difference])

To calculate my previous quarter's numbers, I had to do some dax magic:

Previous = 
var _SelectedPeriod = SELECTEDVALUE('Table'[Year_Quarter], MAX('Table'[Year_Quarter]))
var _QuarterNum = VALUE(RIGHT(PATHITEM(SUBSTITUTE(_SelectedPeriod, "-", "|"), 1, TEXT), 1))
var _YearNum = PATHITEM(SUBSTITUTE(_SelectedPeriod, "-", "|"), 2, INTEGER)
var _PreviousPeriod = IF(_QuarterNum = 1, "Q4-" & _YearNum-1, "Q" & _QuarterNum - 1 & "-" & _YearNum)
RETURN
CALCULATE([Total Difference], 'Table'[Year_Quarter] = _PreviousPeriod)

 Then I calculated my current quarter's numbers which is a bit simpler:

Current = 
var _SelectedPeriod = MAX('Table'[Year_Quarter])
RETURN
CALCULATE([Total Difference], 'Table'[Year_Quarter] = _SelectedPeriod)

Finally, this is where it gets confusion. My logic is if current difference = previous difference, return me current difference. The numbers comes out correct it's just that the grand total isn't there:

Bucket1 = 
var _Current = [Current]
var _Previous = [Previous]
RETURN
IF(_Current = _Previous, _Current, BLANK())

EDIT: Here's a permalink to a sample PBI: https://1drv.ms/u/s!AjMAdFmWoN-JakiK6JBX64vNwSw?e=LJFZyp

Any help would be greatly appreciated!