Issue Description
You have created a rail, in 2D it looks fine, but in 3D appears only in glass, even though you have set a different material in the Railing Settings.
Solution
From the bottom of the screen open the Model View Options > Expand the Railing Options tab.
The Railing 3D and Section/Elevation has been set to Simplified.
With this option active, you can control the rail's Attributes as a whole. You can see the surface material is set to Glass.
To see your Rail in full color and correct materials this setting needs to be changed to Full.
TIP: If your project includes numerous Rails or Railing Systems and your file is beginning to lag, you can reduce the detail level in the Rail options here.