https://bugs.winehq.org/show_bug.cgi?id=35390
--- Comment #7 from Nikolay Sivov bunglehead@gmail.com --- So next thing to check is vartype of default value for this parameter in native typelib. If it's VT_DISPATCH|VT_BYREF, unlikely I think cause only NULL value makes sense as a default, then widl is to blame, if it's stored at VT_PTR type we need ITypeInfo code to deal with that. It's also possible that both parts are broken.