You have a support article on this topic. But your software does not seem to calibrate correctly for my setup to get it to work for the center monitor. I can calibrate my single monitor before switching Eyefinity on, but then it deletes the calibration when switching Eyefinity on. I can choose to continue with calibration while Eyefinity is on, but the sensor is incorrectly sized for alignment with the center monitor. In addition, calibration fails to work properly when just looking at the center monitor for the points.
Your article indicates it’s possible to do tracking based on the center monitor, but the software is not allowing this to happen. It could be because it’s a very large resolution, but why not just cap the resolution to just the center screens resolution and continue with calibration so tracking will just be on the center screen.
https://help.tobii.com/hc/en-us/articles/209529429-Can-I-use-multiple-screens-
I have 3 x 4K monitors and with my latest video card upgrade, I can run all three monitors for simulation games with good performance at the following resolution: 11520×2160
This seems like an ideal product for multi monitors setup for simulation with 1×3 configurations to allow head tracking even if its just based on the center monitor.