Hey, I got the same problem you have. I try to use RNAV LPV approaches, but I'm always to high. The Glidepath never matches up to the PAPIs along the runway. Maybe the problem is, that the final descend into the GP begins too late.
I tried it with Temp Correction on and of, because I first though about the problem in front of the PC, but it happens always. And Temp Correction should only be used, when Temp is outside of the limits (published in the charts).