I just got my z visa processed. Something which hasn’t been publicised much is the crackdown on people breaking their contracts. I know a few guys in this situation, and one was interrogated strongly by Chengdu PSB recently. If you can’t get a release letter you need to provide evidence of wrongful conduct or breach of contract by your former employer. If you just reply that you found a better job, the PSB will come down on you. I was told that breach of contract by a foreigner is technically grounds for refusal of further work permits, so tread carefully and good luck…