first of all thank you very much for releasing the B-17 for P3D!

I'm still using P3Dv4.5 and have an issue with the exterior glass of the B-17. It looks quite opaque and almost like chrome:

On the preview pictures in the shop the exterior glass looks spot on. But I guess they were made in P3Dv5. So I was wondering if either something went wrong during the installation and I installed the P3Dv5 files or if the model is only optimized for P3Dv5?
Help would be much appreciated as the glass spoils the look of this great model a little bit.
Thanks a lot!

Greetings
Tim