Agreement status is always Prefill using Adobe sign in Rest API

When I create an agreement (state INPROCESS) with no prefill fileds, the status is OutforSignature, which is ok.  when I create an agreement (state INPROCESS or following the state flow :DRAFT, AUTHORING, INPROCESS) with at leat 1 prefill field and even when I set the mergeFieldInfo values, the status is always PREFILL, which is not what I expect. If I open this agreement on the Adobe Sign in Dashboard I can see the button enabled "click to send". Is there any missing step to change the status from Prefill to OutforSignature using Adobe sign in Rest API of course.

NOTE: when I tried to force updating agreement mergeInfo I'm getting error because is not valid a statec( DRAFT).