The following information is based on MSFS version 1.13.16.0 and AIRAC 2101.
Issue
If you add a STAR (with/or without an approach) via the WorldMap or any in-games FMC (Airbus, Boeing, Garmin), the result does not look as on the charts, or the aircraft does not follow it correctly.
** Explanation/Reason**
MSFS uses its own internal in-game flight-management. This flight-management is used by the WorldMap and all in-game default aircraft’s, which are equipped with an FMC and/or a Garmin. This internal flight-management has some limitations, which are confirmed by ASOBO/MS in their 3rd Party Developer forum.
This is navdata independent.
Example(s)
ENGM 01R - STAR LUNI4L via INSUV
Jeppesen charts
Default A320 aircraft
Working-Title CJ4 mod (working as expected)
EIDW 28L - STAR OSGAR2X
Jeppsen charts
Default A320 aircraft
Working-Title CJ4 mod (working as expected)
KATL 26R - STAR CHPPR1 via ZELOW
Jeppesen charts
Default A320 aircraft
Working-Title CJ4 mod (working as expected)
Solution
There is no current global workaround. The internal logic must be fixed by ASOBO/MS who according to the latest information, will fix this during 2021. A possible solution is to use the Working-Title CJ4 mod (which uses their own flight-management) and in the near future also the FlyByWire A320 (the guys are working also on their own flight-management).