Some of the recent fixes where added to wrong patches (first patch has base set incorrectly, it's fixed in second patch).
Another problem is that there's something wrong with how the WinRT exceptions are handled/implemented. With code from this MR it's not possible to mix native and builtin ucrtbase and vccorlib140 (we're getting ACCESS_VIOLATION while using exception throwing functions). While it might be not critical I would like to understand what's going on. I'm planning to look into it more. I guess it might be some kind of side-effect of trying to make these exceptions working with older exception handlers.