As graveltrap has pointed out, GTS can be funny about how it does stuff, but at the same time applications such as Illustrator don't always write SVG the same way as each other. It's my opinion that the more tools and shapes you have to use in the application, the more likely it is to cause problems... sometimes the applications are too clever for their own good. It's why I'm sticking with a 12 year old copy of CorelDraw for making logos!