1. Here's why

When using the Depth of Field Effect in Clips and Photos you may notice that Glass and PureGlass Materials are sometimes not blurred correctly.

This is a technical constraint.

Example of a PureGlass Material with the Depth of Field Effect turned on:

Example of a PureGlass Material with the Depth of Field Effect turned off:

2. Workaround

2.1: If you are rendering a Photo, consider rendering two different versions: one with the Depth of Field Effect turned on and the other version with the effect turned off. The two versions can then be blended in an image editor:

External Link: Three Ways To Blend Two Images In Photoshop

2.2: You may find that it is easier to select the glass objects in your image editor if you render a MaterialID output image in Lumion:

Example of a blended image: