BeerSmith 2 Conversion Problems

I just started using beersmith 2 and in my trial and error/exploration in trying to learn the program I noticed a problem. I took an all grain recipe and converted it to an extract or partial mash recipe which seemed to work fine. When I converted the same recipe back to all grain the numbers were different from the original all grain recipe numbers. And in one case it even refused to switch the LME back to base malt. And every time i switched back and forth the numbers would drop more and more. Is this normal for this program. I just don't want to get a recipe locked in and decide to see what it would look like as an extract version and not be able to get my original back. Thanks

I have set all of my equipment parameters. I just started entering my own recipes and even playing with the ones that came with the program. I all cases when I converted from AG to extract and back, all recipe numbers were different. And would never go back to the original settings. So the porter is now deleted because it decided to keep the LME in the all grain version. Wierd