I had a similar issue but it was me that was the problem.
I have a slow Android phone and things went too fast. I discovered that I was applying multiple forces, and the frame rate meant I was applying the overall force with much less impact because of the delay. e.g
Check your code and look for areas where
your code is affected by frame rate. I can say from experience that frame rate is not an issue for the built-in Physics system. I plotted the data on a line graph for different systems, and it's very accurate even across different frame rates.
