Beginner stuck with getting value from a blended source

Hello,

I am still new to Tableau.

I am trying to get the corresponding [MTD] value from a blended source "Working days" within my main source "KIA_SALESCUBE"

Because I am using Month filters it is getting the corresponding month value but I need the corresponding day value in my Current working day.

How do I get around this?

The Working days data looks like this,

Any help is appreciated.

Thank you