It may help to set the models albedo plus having the Sun light turned on or at least one dynamic light having the model within its range:

- Models without an action need initially be set through the WED to a low albedo from -100 to +10.

- Models that are controlled by an action should, at least initially, in the action be assigned light= off, transparent= off, bright=off, unlit=on, and a low albedo between -100 to +10.

hope this helps,
tindust