Rest (unassigned) has no file output

[cecofuli]

How can I save the Rest (unassigned)
For example, I have a teapot with CoronaMTL with self-illuminated material.
This geometry will be rendered in the Rest (unassigned).
But, In the VFB  drop-down menu, I don't see this layer.

Thanks.

[Ondra]

reworked the unassigned element, now it is possible