I don't set pin/password for my device.
The first time I use TWRP, it cannot mount internal storage. So I go ahead and wipe the storage. This allows internal storage to mount and I can create NAndroid backup for my phone.
Then I restart the phone and go through the setup process from beginning.
Then I restart into recovery (TWRP) again, it asks for the encryption password again. So I in effect cannot see what's on my internal storage and cannot see how can I ever restore such backup I made earlier.
What did I do wrong? How can I backup and restore using TWRP without setting pin/password for my device?
(For the record, set 0000 as lock screen PIN and use it as decryption password doesn't work for me)