It may be or may not, that Chinese lost interest in it due to lack of our present govt. interest and acknowledgement for their best efforts for defence and economic support,. When we running for US embrace, how could they keep same fast track involvement.Most probably certain roadblocks have been encountered. It's understandable that PAF will not want to talk about it, who does? Could be engine, could be AESA or any other thing for that matter.
It is only my fear; I have no access to information to the actual cause of this protracted delay beyond one's imagination with complete hush.