Imported Substance materials behave incorrectly when applying UV rotation

Reported in SF [Link Removed] and on the forums at https://forums.unrealengine.com/t/substance-3d-materials-not-reflecting-light-properly/2718611

UV rotation behavior is incorrect for Substance materials that are imported into Twinmotion 2026.1. When applying a UV rotation, lighting and reflection handling are noticeably incorrect at any rotation aside from 180 degrees. At 0 degrees, the material is darker than is should be, progressively brightening until 180 degrees.

This behavior is unique to imported SBSAR files. The samples included in the Twinmotion library do not exhibit the same problem.

This is a regression introduced in 2026.1. A video demonstrating this problem is in the forum post. Attached a sample scene showing the issue.

Use attached project or a new scene

1. Download any Adobe Substance material
2. In TM 2026.1, import the material to a scene
3. Apply the material to an object
4. In UV settings, apply a Rotation

Result: Lighting response for the material will be noticeably incorrect as the UV rotates