why always Not Validates for edit Formula

[jayshu]

Hi，

I am implementing Workforce Analytics on Hana but it always shows not Validated when edit formula.

it always shows the error"

Invalid

String reference not set to an instance of a String.
Parameter name: s"

@sorenhojby @former_member18089 @Marie_Mayoros 

[jayshu]

it always shows "Invalid String reference not set to an instance of a String. Parameter name: s"