AEM Assets PDF thumbnail not generated correctly after implementing PDF Rasterizer Steps in Existing Update Asset Workflow

Hi , 

I  have tried the PDF Rasterizer  steps in my local environment suggested by Adobe. As part of this activity there are some certain steps have been included as per PDF Rasterizer  and updated the existing Update Asset workflow and preventing the thumbnail and web rendition generation for PDF by default . Renditions and thumbnail should be generated by including the customs steps (PDF Rasterizer Handler) as per the article but it is not happening. Has anyone experienced this issue? Please suggest.

Thank You.