Maybe I misunderstood what you actually tried to do. If you tried to copy the .lnk file from the start, but that’s what you’re saying didn’t work properly, then I’m sorry to say I don’t know why that would be the case. BP performs a standard file copy just like if you do it yourself through Windows Explorer, so if that didn’t work then my guess is it’s due to something about how the shortcut file itself is formed, though I couldn’t say what exactly that would be. Maybe it doesn’t like %windir% and instead wants a full filepath.
However, when you first posted about this issue, I thought you were describing that you somehow had tried to enter this value into the BP copy file/folder interface, which I’m certain will not work properly:
%windir%\System32\rundll32.exe shell32.dll,Control_RunDLL timedate.cpl,,0