Definitely has to be sensor bar position. Mine is on the bottom of the TV and from where I sit, it's pretty much parallel with the remote
that could be true. mine is right in front of the bottom of the TV, but sitting on my couch the wiimote is naturally about a foot higher than the sensor. it's better than having the sensor on top but maybe that's what causes issues anyway. one other control issue I had was sometimes the aiming controls would invert if I wasn't in a specific zone of space. like if I leaned back and tilted the wiimote slightly up, everything got whacky. I'll bet my setup has something to do with that as well.