Hey RobertG117,
that seems to be an obsolete option that wasn't removed
I'll see to it that it doesn't cause any more confusion.
If we want to use a skybox, we make a Root Template and manually place that around the appropriate part of our level.
We have a few examples of that. If you search in the
Root Template Panel you'll find for example ATM_temple_Imp_Skydome_A. Do mind, these are special material we designed to make it look like there's a lot of depth in there.
If you want to make a basic one yourself. Make a copy of one of the defaults. F.e. ATM_Skydome_A and assign it a custom Visual Resource ID. These can be found in the
Resource Manager. For this again, I would suggest making a copy of one of the existing ones like ATM_Skydome_A. Then double click the resource and change the Material.
Sincerely,
Kevin