For GPS approaches, we get all our data from a real-world airline, so we have a big database of a) what runways that airline thinks exist, and b) where those runways are (lat/lon).
There's nothing inherent in the design that keeps this GPS approach data in sync with the scenery you have installed---so, for instance, if in the real world, a runway was moved (due to new construction) or renumbered (due to changes in the magnetic variance at the location), and the airport in X-Plane hasn't been updated, the GPS procedure will absolutely not work---as far as it can tell, the runway it expects to exist simply does not.
This may be the reason approaches appear to be missing now. The next beta will have a new feature to make reporting this easier.