Okay...that does make a difference. You may have something in the drain pump or drain line that is causing the odor problem. Leaving the lid open is a plus, but if you have something stuck in the drain somewhere, it will create musty odors. Is this an Oasis, or standard top loader? Could you please provide me with a model number (located around the lid opening) so I can determine what type of pump you have and how to access it?
Is this a FRONT loader, or a TOP loader? You have this listed under front loaders, but stated in was a top loader. This can make a difference in how to diagnose. Can you please post back with your model number?