[!]NOTE: Decrypting data is not currently supported. MTP also does not work, but you can use adb to push and pull files.[!]
Team Win Recovery Project 3.x, or twrp3 for short, is a custom recovery built with ease of use and customization in mind. Its a fully touch driven user interface no more volume rocker or power buttons to mash. The GUI is also fully XML driven and completely theme-able. You can change just about every aspect of the look and feel.
-Reboot into fastboot
-use the command: fastboot flash recovery_ramdisk twrp-X-X-X
CHANGELOG for 3.2.1-0:
-minui fixes (cryptomilk)
-Better android-8.0 compatibility in ROM trees (Dees_Troy)
-Fix missing library in android-8.0 (nkk71)
-Fix inconsistent SDCard naming (DevUt)
-Default to TWRP restore instead of adb backup restore to fix restore on fresh TWRP boot (jlask)
-Allow restoring adb backups in the TWRP GUI (bigbiff)
-Fix gzip backup error in adb backups (bigbiff)
-Fix a bug in TWRP's backup routines that occasionally corrupted backup files (nkk71)
-Better support for installing Android 8.0 based zips due to legacy props (nkk71)
-Support vold decrypt with keymaster 3.0 in 8.0 firmwares (nkk71)
-Decrypt of synthetic passwords for Pixel 2 (Dees_Troy)
-Support newer ext4 FBE policies for backup and restore in libtar (Dees_Troy)
-v2 fstab support (Dees_Troy)
-Bring TWRP forward to android 8.0 AOSP base (Dees_Troy)
-Various other minor bugfixes and tweaks
-Added splash2 partition as mountable to obtain failure logs.
-/cust as TWRP settings holder
-fixed a quirk with Data formatting
-Dil3mm4 black theme
-error 7: your phone somehow doesn't mount /system, never happend on my PRA as of now, this has to be the result of bad operations;
-My LOS15.1 it's discontinued, the thread it's even closed, I don't know why you're considering to use it.
As of now, I'm not interested in doing any further TWRP releases as the easiest way to avoid problems over Huawei treble enabled devices, it's using fastboot plus Huawei Stock Recovery.
When TWRP will be safe enough, I'll surely re-build 'em.
When you're in TWRP, try to browse/mount data partition. If you can't or if internal storage occupied space says "0 MB", then you're encrypted. You can remove encryption by flashing DM verity (a zip that disables encryption, look for it in XDA search) immediately after you flashed a ROM/GSI, and before flashing GApps/Magisk.