Do you have FTX PNW or True Earth Washington?

https://orbxsystems.com/forum/topic/105160-orbx-pnw-and-taxi2gate-ksea-airport-compatibility-guide/?tab=comments#comment-948175

Pretty straight forward, but also what do you have selected in ORBX Central as your library insertion points? It's crucial that it's correctly set to avoid repeated layering issues.

@Dave_YVR

I have this:
FTX Pacific Northwest, and found the files:

FTX_SCA_objects_KSEA_PLC.bgl
ADE_FTX_SCA_KSEA_CVX.bgl
ADE_FTX_SCA_KSEA.bgl

and rename them with I add .OFF like this

FTX_SCA_objects_KSEA_PLC.bgl.OFF
ADE_FTX_SCA_KSEA_CVX.bgl.OFF
ADE_FTX_SCA_SEA.bgl.OFF

I did that because I did that with LAX, og I think I was need to do the same for SEA. And after that I saw the graphic problems when I open SEA Airport up in my P3D v4.5

Best

Jammin16

What about you insertion points?

@Dave_YVR

Hi Dave,
I have now follow your second link to how I can fix my problems and now it's work fin for me. 
Thank you very very much for your time and help, I wish you a Happy Easter and stay safe.

 

Best

Jammin16