Hmmm I made three fully automated testflights with auto-land so far, with manual flight path programming, and the autopilot and also the ILS always worked flawless. Impressive how this old retro computer system cannot draw curves on the screen but the plane itself is cutting corners flying a smooth path. Love this plane, it is awesome!
I was especially impressed that the internet said Bergen Lufthavn ILS frequency 109.90 with 27nm range, and somewhere below 30nm the A300 slowly begun to catch the ILS signal and started following the glide path down. I made it even more difficult for the MCDU when testing the systems by programming a flight path with vectors directly above the landing runway, but the machine left the pre-programmed MCDU waypoint course to catch the ILS, just like it should. Awesome.
(I have not tested VNAV in the MCDU but manually went up to 10.000 and back to 3000 to catch the ILS. I rarely use pre-programmed MCDU-VNAV.)
Everything seems to be fine with the autopilot. I never fly by hand and found no problem with the automatic systems so far. Maybe you encountered a glitch in the simulator or a simbrief problem.