I believe ResumeFlow should advance the flow without a special control. It is possible that the SLA did not actually fire or that there were errors during ResumeFlow. Do you see a message in the work object audit about the SLA action being fired? If not, then something is amiss in the SLA. Does the flow action have a validate rule or post processing activity or data transform applied to it? Could there be errors there. Check the Broken Process queue to determine if there was a problem.
@VenkatRamanM : I have also used ActionAutoSubmit. Prior to Pega 7.1.8 , ActionAutoSubmit used to work. But it does not anymore. I have also tried the steps you have mentioned. Does not help. doSubmit also does not submit the flowaction.