#REF with Date with GETPIVOTDATA

I have a row with dates, 2018-01-01, 2018-02-01 ... 2020-12-01, that I want to reference to, in a GETPIVOTDATA formula. I've managed to reference to another cells for Gross Profit, AM, Region, and Team, but can't figure out the Month.

GETPIVOTDATA("[Measures].[Sum of Gross Profit]";$BD$4;"[Data].[AM]";"[Data].[AM].&["&$A$4&"]";"[Data].[Month]";"[Data].[Month].&[2018-01-01T00:00:00]";"[Data].[Region]";"[Data].[Region].&["&$A$1&"]";"[Data].[Team]";"[Data].[Team].&["&$A$2&"]")

I believe it has something to do with T00:00:00 but don't know what to do in the GETPIVOTFORMULA formula.

assuming real date value then you might try something like below as the parameter

"[Data].[Month].&["&TEXT(B$1;"YYYY-MM-DD\Thh:mm:ss")&"]"

modifying B$1 to be whichever cell is holding the date (assumed you're storing results in a matrix and formula will be copied to right)