Device: Xiaomi Mi 9
ROM: [[ROM][10.0][Xiaomi Mi 9][UNOFFICIAL]Pixel Experience AOSP[2020/04/11], ROM for the Xiaomi Mi 9
I tried to upgrade my ROM from an older to a newer version with a clean install whilst keeping the Internal storage of my Mi9.
The Device has been encrypted with FBE protected with a pattern.
While performing the upgrade TWRP did sucessfully decrypt the data.
Now after performing the update the phone was only able to boot into TWRP (3.3.1-62) and wasn't able to decrypt /data/media/0
I also tried do decrypt via adb shell with
twrp decrypt 563258
following the TWRP commandline guide
 [⭘↓←]  [⭘↦↑]  [⭘⭳⭘]
but this also failed.
Only way to make the phone boot again was to format data partition in TWRP. Unfortunately I did not save my backups on a different device, so to say all my backups and data is on the encrypted drive, which I can't access anymore. Before wiping I saved an image of /dev/block/sda31 which is the data partition I'd like to recover. I am also able to access the keys or data at following locations:
/data/misc/vold/keystore/ /data/misc/vold/user_keys/ce /data/misc/vold/user_keys/de /data/unencrypted/key /data/system_de/0/spblob
So my question now is how to regain access to my data. So far I tried several approaches, none of these lead to success. My hope is that there is a possibility to mount the image, using the available encryption keys. But that's at this point beyond my technical skills, so maybe here is someone with another idea how to do this.