that´s a known and from ASOBO/MS confirmed limitation in the sim. The FBW A320 uses still the internal logic of the flight-planning and that´s the result. This is also independent of the data you use (stock data from NavBlue or our data from Jeppesen). Sorry, we can only wait on a fix from ASOBO/MS because we can only offer the data but we have no influence of the interpretation of it … Also, this happens for ALL in-game aircrafts because all uses the internal logic of flight planning of the sim.
But what I can highly recommand is to try the Working-Title CJ4. The devs have developed a own, complete independent flight-planning for their FMC and here you see, how it will be worked, when all will be interpreted correctly and when the linkage between STARs and approaches are working.
Here the MORGO 1A to RWY 30 into Hobart:
You see, the same data as the sim uses but a perfect STAR with the VOR approach. No truncated waypoints, no strange turns or similar else. It´s really worth to try. The FBW guys are also working on a independent flight-planner for their FMC and I´m pretty sure, that then we have a good basic package.
Sorry, but the in-game aircrafts (nor the route-planning in the world-map) are very useful for IFR.