controls not working in build compared to editor

I have a network racing game in development.

I have the steering and acceleration axis assigned to a PC xbox controller stick and triggers.

When I launch the game in editor, (then choose host as its a netgame) everything works properly.

When I build the game, upon starting the host the car accelerates maximum forward, and maximum steering to the left.

If I exchange the axis to be keyboard control, everything works as expected.

I have zero errors in my output log.

I've tried altering dead zones etc, although this is futile if it works perfectly in editor.

Any ideas? been at this for a few days.