Hi, are you using any tools like MSFS Addon Linker to link the plane into your community folder from some external location?
If yes, please move the [inibuilds-aircraft-a300-600] folder to the community folder directly, then re-install.
If not, then please ensure you are running the latest version of iniManager (v2.3.3). Uninstall the A300-600 from the iniManager, and check your community folder there is no [inibuilds-aircraft-a300-600] folder inside. Then reinstall the aircraft.
Thanks!