Unable to view the thumbnails for 3D web styles installed in Portal for ArcGIS after upgrading to ArcGIS Enterprise 10.9.1.

Workaround

Workaround Option #1: Restart Portal for ArcGIS service.

Workaround Option #2: This workflow creates users' own styles and does not automatically update with each software upgrade.

Add 3D symbols to a new style folder and share them as 3D web styles.

1. In the ArcGIS Pro project, navigate to Styles in the Catalog pane and add a new style folder.
2. Add the desired 3D symbols. In this example, 3D Vegetation - Realistic is added.
3. Open the 3D Vegetation - Realistic folder, and copy all the symbols.
4.  Add the copied symbols to the folder created in Step 1.
5. Publish the folder to Portal for ArcGIS using the Share As Web Style function.
6. Publish the style in Portal for ArcGIS. The styles can be added to a group so they can be used by multiple portal users.

Repeat this workflow for the desired symbols categories.

Steps to Reproduce