HMR: Add P-Early-Media Header to Reply

Hi Team
I am having issues with applying an HMR.

I want SBC to add a P-Early-Media with value supported in its response (particularly the 183 Session Progress Response)

So I wrote the following HMR:

sip-manipulation

        name                           AddPEM

        description                   "Add P-Early-Media"

        header-rule

                name                           addPEM

                header-name              P-Early-Media

                action                          add

                comparison-type         case-sensitive

                msg-type                     reply

                new-value                   supported

I tested using test-sip-manipulation and it worked as expected. The issue though is with applying it.
INVITE comes in from Realm-A and leaves via Realm-B.
I want to add the PEM Header when replying to INVITE via Realm-A. So I applied AddPEM to the out-manipulation of Realm-A. When I make test call, it just does not get added.