NOTE: Areena, I wrote the text below assuming you are setting workflow to Released before looking for grades in the gradebook. I have never seen grades show up in the gradebook until they are set to Released. If you aren't seeing the grades when they are released, read on.
I'm not sure if it is related, but we had a similar problem. In our case a grader had begun working and was not happy with the new (we just got 3.2) process for saving assignment grades. (We use advanced grading and grading [marking] workflow.)
To reduce her number of clicks we turned workflow off. She had already graded and released a few grades before I turned off workflow. I assumed anything already showing up in the gradebook would still be there.
I was wrong. All of the grades she entered after I turned off workflow showed up in the gradebook (grader and single view), but the first ones did not. However, the grades and feedback were still there and seemed to show up in user reports.
The rubric settings and the feedback the grader had entered were still visible (so still saved) when we went to the grading window for the students.
I assumed we broke the path to the gradebook by turning off (or likely turning on) workflow. We were able to get them to show up in the gradebook by simply re-saving them in the grading window.
Is there any chance you changed the assignment settings after grading began? If so, try simply saving them again and see if they show up.