This will a ticket about the problem of new input system for modders.

Already spoken with Sumrak. I know the actual new input system, need some tweaks for sure. But I want to give you a bug that need to be fixed, so modders can use the new input system.
This "bug" can be already thinked by the DayZ Dev team, but a feedback was needed so we are sure that you are aware of this.

Actually the new input system in stable branch (12/01/2019) have some problems for modding :

• You can register new input, and new group. The problem is when you are exporting the .xml file when registered all this inputs/groups.

GetUApi().RegisterGroup( "Expansion", "STR_USRACT_GROUP_EXPANSION");
input = GetUApi().RegisterInput( "UAGps", "STR_USRACT_GPS", "Expansion" );
if ( input )
{
    input.BindCombo( "kM" );
    Print("[KeyBindingSystem] BindingCount : " + input.BindingCount());
}
GetUApi().Export();

I'm using this code actually. The exporting works fine for the profilename.core.xml

It's creating these inside :

<group name="Expansion" loc="STR_USRACT_GROUP_EXPANSION">
        <input name="UAGps" />
    </group>

It's exactly what excepted.
The problem is for the file profilename.dayz_preset_User.xml .

It's actually not creating the input line with the btn inside, we actually except this :

<input name="UAGps">
    <btn name="kM" />
</input>

So when you go to the keybinding menu after everything exported and restarted the game. You have the tab Expansion that working fine but nothing inside : link screenshot

After a lot of research, I'm pretty sure the bug is, when you use the function "export", it's not exporting the profilename.dayz_preset_User.xml file.
Even tried to add directly to this file the input line when the game was not started and restarted the game.
The problem, the game reset everything inside this file that are not added inside default preset.xml file.