Try please!
Too lazy! 
I tend to believe you that this was the outcome.
I guess the reason is that % is treated as a unit in Mathcad 15 but is just some of multiplication operator in Prime. If you type a % sign in Prime you automatically get a placeholder to the left of it - so % stands for __*0.01 and you are forced to provide the first operator.
So the result should be read as 30 * 1% which is kind of correct and silly at the same time.
In Prime you can get what you want using the "Result Format" menu on the "Math Formattting" ribbon. The converter should "know" that and do its job better.
Thanks, I know it.
Mona Zeftel has written me that it will be in prime 2 as in Mathcad 15. But now we have in PTC Prime with this error and not Mona 
