What if Parameter start,end value bug

HI all,

Ive been trying to get the whatif parameter range based on some value of a table

however it seems that the start and end variables doesn't work well with measures.

here is an example

1. I first created a measure called current quarter to intake a certain slicer value. so when I use my slicer this measure will change
   Current Quarter = SELECTEDVALUE('Mapping Period'[FY]) //'Mapping Period'[FY] is a slicer value
2. I then created a measure of the desired range i want the what if parameter to be (take note I have input my previous measure as part of the filtering criteria):
   Current quarter AR = CALCULATE(SUMX(FILTER('Table-FCF','Table-FCF'[ACC] = "Accounts Receivable" && RELATED('Mapping Customer'[SECTOR]) = "company" && RELATED('Mapping Period'[FY]) = [Current Quarter]),'Table-FCF'[Value])/2000000)
3. I then make this measure the start and end values of the range of the what if parameter
   what if parameter AR  = GENERATESERIES(-[Current quarter AR] ,[Current quarter AR],1)

When i do this the start and end values are all wrong and are some absurd number.

However if I change the Current Quarter measure to:

Current Quarter = "Q2 2020"

the correct start and end values are set however i am forced to change the code every quarter.

how do i make so that when i slice by my quarter the start and end values of the whatif parameter are displayed correctly?