Studio Drummer never saves my mapping

Hi all,

I've been using Studio Drummer more regularly lately. However, it seems that I cannot find the way to properly save my custom mapping. Even if I press the save button at every mapping changes, every time I close the software, the custom mapping I had saved is exactly the same as the default one. It will even sometimes revert to the default when closing the VST window and then opening it again. Has anyone else faced this issue before? Thank you very much