Revit 2026 to Twinmotion 2025.1 – Mullions Displaying as Glass

Development Getting Started & Setup
1

Hi all,

I’m running into an issue with the latest releases of Revit 2026 and Twinmotion 2025.1. When exporting window families that include built-in mullions (glazing bars), some display correctly in Twinmotion—while others, using the exact same family type, appear with the same material as the glass, making the mullions look transparent.

This wasn’t an issue in Revit 2025. The same families exported just fine previously, with mullions showing their correct frame material. Now in Revit 2026, it seems Twinmotion is misreading or misassigning materials during the export process—especially for nested geometry inside window or curtain wall families.

Is anyone else seeing this? Any workarounds or settings to override the material mapping?

2

I am having the exact same issue. On random windows it appears as if the glass is in front of the window. Very frustrating as I am working in revit 2026 now and can’t go back to 2025. I may have to purchase and subscribe to a different render software if it doesn’t get resolved soo as it is affecting workflow. Any help is appreciated.

3

Hi, I was having the same issue and it was driving me mad. I ended up uninstalling Revit 2026 and reinstalling. All now seems to work fine. Cheers

1 Like