Thanks for the download, I'm glad you like it! The disappearing body parts is a VRoid feature where it masks the parts of the body covered by the clothes so it doesn't clip through with movement but its a super simple fix. On the Texture screen for the clothes, there's a tab called 'Skin Mask' that, when opened, will have a layer with a blacked out section. To unhide the parts you want, draw over the black parts with white and that'll delete the mask. Similarly, if you want to hide a body part, color over it with black. Hope that helps!