!> OxygenOS 11 installed on the device may cause a lot of weird various issues including a potential hard-brick if you would flash EDK2 to the boot image. Please consider to downgrade firmware to OOS 10 (and install any custom rom over it if you like) before doing anything, especially if you want to flash EDK2 to boot partition.
The same thing if you have any custom rom installed over OOS 11 firmware. You still need to downgrade to OOS 10.