Okay, are you aware of the latest news on the mod? The Development version is now installed as a standalone aircraft, not a mod to the default A320. But the Stable version is still a mod to the default A320.
If you want to install the development version, make sure you delete everything A32NX mod or FlyByWire mod folder in your community. delete them all, then use the installer to install the Development version again.
When you start the sim, you won’t be going to the Airbus A320 anymore. But instead, you need to choose the FlyByWire A320 (Leap) aircraft, which is a standalone aircraft.