Please check the binding, there are two types of axis binding for T6 antenna.
{action = axis_cmd.HOTAS_Throttle_T6_Abs , name = _(cmd_names.HOTAS_Throttle_T6)},
{action = axis_cmd.HOTAS_Throttle_T6_Abs_Slide, name = _(cmd_names.HOTAS_Throttle_T6_Slide)},
One is for mini-stick like axis, that after release the axis, it will be recentered.
For this one, the input determines the move speed (like TDC)
[*]The other is for slide like axis, it will remain the last position (like wheel?)
For this one, the input determines the final position
You may need to change your binding to proper one