Any idea what's causing this? I don't have any other KLAS AFCADs or scenery installed.
The only thing that can cause this, is another scenery. Either it's an AFCAD, or it's a mesh. You might have a conflicting AFCAD, even if you haven't installed yourself, since they usually come with AI Traffic packages, like My Traffic or similar.
I assume, of course, you have the current version of KLAS (1.1)