Unity iOS - ARCamera is set to (0, 0, 0)

Hello,

I have a strange behaviour on the ARCamera object (but only on ARKit device compliant, ie: iPhone X for now).

When all trackers are lost, the ARCamera is set to the position (0, 0, 0), even if I set another position in Update() function (I would use the gyro: trackerless mode which is working on all my others devices).. 

I need to have the setting "FIRST_TARGET". It works fine for others devices (iPhone 5 and 6 and even under Android).

I hope help or a bug fix  !.

Thanks in advance,

Eric