Could you help
Good to hear!
If you have sound / connexion issues in 11.5 it could be because you flashed it over 11.1 (hopefully CN).
Fix for that is to flash small partitions manually with TWRP.
@alexeei should soon write a walk-through about fastboot flash. But meanwhile feel free to go to Telegram and look for group Lenovo Z6 Pro.
Every Z6Pro owner is welcome!
Oh and remember... Never install google account manager on Zui 11.5 or use googleinstaller.apk