Use Subtotal Sum in Matrix for a Dynamically formatted Column

Hi SeungLee95 ,

Create a clean numeric measure for calculation.

SR_Actual =
IF (
SELECTEDVALUE(COUDashboard[APType]) = "Classic",
BLANK(),
SUM(COUDashboard[ServiceReadiness])
)

Use a second measure for display using format string or Conditional Formatting.
Instead of showing "N/A" directly in the DAX measure, use Conditional Formatting to display "N/A" as a custom string for rows with APType = "Classic".
Create a DAX measure just for formatting, but you can’t use this for subtotaling, it’s for visual override only.

DisplayLabel =
IF (
SELECTEDVALUE(COUDashboard[APType]) = "Classic",
"N/A",
FORMAT([SR_Actual], "#,0")
)

Now create a Matrix
Add the SR_Actual measure to your Matrix.
Click the measure in the Values area > click the arrow > Conditional formatting > Field value.
Choose "Based on field" > DisplayLabel.
Select to apply to "Values only".

Set the output as custom text,  Power BI will now use "N/A" for classic rows and actual numbers elsewhere.

If this post helps, then please consider Accepting as solution to help the other members find it more quickly, don't forget to give a "Kudos" – I’d truly appreciate it! 

Thanks and regards,

Chaithra E