I also think the problem of the YJ Generation is their unspectacular return.
I mean there was the storyline when Superman got blind and had to be saved from the Superman Revenge Squad.
This would have been a great moment to bring Conner back out of nowhere, but they gave the spotlight to Supergirl,Kenan,Superwoman,Steel and Luthor.
I mean at the moment they are here yes and have adventures, but others are in the spotlight.