Make sure you manually delete the old version of anything with A32NX or FlyByWire mod folders from your community folder. Clear it out so you can start over fresh from scratch.
Then also make sure you’re running the installer version 1.2.0 or later and use it to do a fresh install of the new stable version.
In the sim. It’s shown as a new standalone aircraft called FlyByWire Simulations A320neo (LEAP). Don’t pick the default A320 anymore.