UPDATE: A TCP/IP solution didn't work for me either, I had the same problem where the hidden process needed focus in order for the lvinput.dll to work.
Main takeaway: lvinput.dll is a terrible library that exhibits strange behaviour and has with lots of bugs that have been documented numerous times over the years but NI still hasn't fixed them.
SOLUTION: Use the XInput.dll shipped with Windows as per the instructions outlined by ehrlich here. This also enables the setting the vibration state of the xbox controllers. VIs attached - requires controls/indicators from the Makerhub Xbox library.