a-asset-item does not preload

[mnutsch]

When adding a .obj file like the following, the asset does not preload:

<a-asset-item id="Headphones-obj" src="static/Headphones.obj"></a-asset-item preload="auto">

[mnutsch]

Also tried:

<a-asset-item id="Headphones-obj" src="static/Headphones.obj" preload="auto"></a-asset-item>