Asus Zenfone 5z giving distorted and broken sound, stuttering sometimes, reset and restart did not solve problems. However, other wireless headphone ( JBL endurance run BT and Logitech wireless) working fine with the phone. Whereas, JBL tune 230NC TWS working with other phones.
Reset TWS, restart phone, clearing Bluetooth cache done. Did not help.
So, it would seem that Asus Zenfone 5z and JBL tune 230 NC TWS are not working with each other.