After updating to Version 3.9.0 it seems that assigned Attribute>Basic>Layers within the Wall / Window etc. definitions have been scrambled. I reinstalled Version 3.8.1 and the same file opens with the correct Attribute>Basic>Layers.
Hi @Maynard_Leon you are right. This is an error introduced in the 3.9 update. We will fix it as soon as possible. In the 3.10 RC1 update this error doesn’t happen.