As you can see from the attached screenshots, PAPIs for both 24 runways at KLAX works just fine, in FSX.
KLAS and KLAX don't have anything in common in relationship with PAPIs, since at KLAX they are entirely custom-made, while in KLAS are plain standard AFCAD.
And yes, I see the issue in KLAS, which happens only with FSX, it works fine in P3D so, we might have possibly created an issue to FSX with a recent update to improve compatibility with P3D. We'll look into it.
So yes, there's a problem in KLAS, but KLAX works just fine. What other sceneries you have installed that might affect the KLAX area ?