You do it your way and I'll do it mine. I DON'T LIKE LOS RECOVERY!! And I DO NEED the backup option, thank you very much.
Recovery was never meant to access /data partition and do backups like this.
Ever thought about looking around seeing all the shiny new userspace backup solutions out there? Seems like you're stuck somewhere in 2016.
I guess you neglected to read the post that tells you how to keep LOS from re-encrypting the data partition. I DON'T WANT IT ENCRYPTED!! I have been using Android devices for close to a decade without encryption and have NEVER had a problem. I have a belt. I don't need suspenders too. (And LOS when it was Cyanogenmod.)
Good luck then. You will neither get support from my side nor anyone over at official lineageos, even if your issue might not be related to decryption at all.
And yes there are in fact various issues you can run into from decrypting, but whatever, you seem to be thinking you know everything better anyway.