Fred,
Can you walk me through how you are doing it?
There are many ways to do any operation in BeerSmith, so it is possible that one way works and another has a bug in it.
I just did some quick tests, but did not duplicate your problem - most likely you are creating your mash profile in a different way than I am.
Also - I think I need to add you to the beta test team - you seem to have a great eye for picking out bugs!
Cheers!
Brad