Workaround i found is that if i connect both headphones individually i.e in order Right first and left second. It works perfectly fine but it won't auto reconnect i.e you have to reconnect everytime which is pain in the .....asus needs to fix this!!
I have exact same problem i.e no matter what, it just won't connect in Stereo mode, both connect in mono mode. Headset is Lennova HT10 which uses APTX. Same headset is able to connect successfully in stereo mode on PC & other devices like One plus 6 ...
