I've recently installed some of the BSS sceneries around the airports I fly. However, no matter how I have my scenery library layered, the photoscenery always overlays my taxiways and such. Even when I have the airport scenery prioritized in the scenery library. Why is this? It's happened both at KSMF and KOAK.

Because that is what photoscenery does.

...There's no way for photoscenery and airport sceneries to coexist...Er, okay?

I've used other photosceneries that cause no issue though...

Such as....?

Megascenery.

So with Megascenery at the top of your scenery library, the default FS runways show through?

With my airports layered above Megascenery, my airports properly overlay the photo scenery. This is not the case with BSS. Haven't tried a default airport.

 

And even with the BSS, the runways still properly show through, but not the taxiways and ground textures (within the AP perimeter).