These have the auto adjuster ratchet on the gearbox side, its inside that rubber boot on the cable, if these get pulled tight, they often lock up, or refuse to adjust, when it comes new, there is a plastic clip that keeps it done up, then you fit and release and it will find its position, so i would have said when the clip came out, it pulled the ratchet tight and now its either stayed tight, or not correctly adjusting.
You can try removing the cable from the box side, then using the clip that comes on the adjuster, if its still there, lock the adjuster up tight, then refit, and release, then pump the pedal a few times, it should adjust, but i recon that clicking you hear is the adjuster slipping or locking.