When pointed out to the aircraft developers, they indicated that the aircraft behaved per design, and the Nav Data was incorrect. Attempting to insert Direct-Tos to subsequent waypoints in the arrival still drew a path ‘infinitely to the west’ and never connected to the airport.
The developer’s rationale was that the ETA spikes significantly from the last normal waypoint to the next, indicating that the FMS finds the distance to next waypoint to be incredibly high
The missing info is as follows:
Windows 10
MSFS 2024
inibuilds A300 Premium
No other non-standard hardware or software pertinent to the issue
So, this is not navdata related, and the major reason is that the base scenery (which was designed for 2020) is not fully MSFS2024 SU3+ compatible, even when you install another package, and when the 3rd party dev means it is compatible. It is not as you see.
By the way, you can make this test on your own. Uninstall/remove both packages from your community folder, then check the MCDU leg page in your Inibuild A300.