TWRP 3.2.3-0 can’t decrypt an encrypted LOS15.1.
i created an issue on github:
is anyone working on this?
a workaround exists, thanks to AnotherElk by upgrading from 14.1 first (Updating LineageOS 15.1 for microG via TWRP + feature test)
but this is not a good solution for the regular user (¬ based on the current 8.1 encryption)