Glad you solved it finally.
If I had to guess, in your case I wouldn’t entirely rule out the latter option. :)
BTW: Not a good idea anymore to copy DLLs in a system folder manually these days in general. Even if the ‘bitness’ is correct, many Microsoft DLLs compiled for Win 8 or 10 will flatout not work on Windows 7 due to dependencies on other DLLs or system components. One can’t even safely swap many DLLs between different Windows 10 versions.