Approval of Earmarked Funds Fiori Application in Fiori Inbox

Dear Experts,

I'm using custom workflow by taking copy from standard workflow for Earmarked Funds Scenario("FMRE" BOR, for 'WS99900008' Workflow template ID, 'TS99900020' Task ID). I'm also configured the approve / reject decisions in SPRO for fiori my inbox. I have mentioned the approve and reject reason in "FMRE_WFDEC_RSN" transaction. The problem is when I approve/reject through fiori inbox it won't reflect at the backend. Its triggering the /IWWRK/IF_WF_WI_BEFORE_UPD_IB~BEFORE_UPDATE method while approving through fiori inbox. Currently i'm updating the workflow container values in this method, but it doesn't make any impact. How can i implement decision in this /IWWRK/IF_WF_WI_BEFORE_UPD_IB~BEFORE_UPDATE method for this case? Any suggestions to over this issue? Thanks in advance