I had the same problem with some of my designs, it seems as if they are overlapping, I figured out that the problem is in the name of the file. The "_" in the file name is the culprit.

The program sees this as a split file and then overlaps the designs. If you rename the file it become its own design again. It seems that the proram does this for files that are to big to write to the card for your machine and then puts in the "_". And some designs that we download has this in its name already. I originally had put every design in its own folder to "un"impose them from another, and luckily realised what the problem was when one of my designs was split.