Encrypted startup disk converted to LUKS2 format says wrong password

[Jim]

Converting encrypted startup disk from LUKS1-> LUKS2 format - the original passphase works but adding / changing keyslots/passphrase after conversion never work and get "wrong pass" message at startup.
External, non-startup disks work fine with LUKS2 Argon2 hashes.

Reconverting back to LUKS1 format I can again change / add keyslots/passphrase successful at startup.

Submitted as a Cryptsetup bug but parameters of luksDump looked correct they said.

1. Description: Ubuntu Bionic Beaver (development branch)
Release: 18.04

2. cryptsetup:
  Installed: 2:2.0.1-0ubuntu2
  Candidate: 2:2.0.1-0ubuntu2
  Version table:
 *** 2:2.0.1-0ubuntu2 500
        500 http://us.archive.ubuntu.com/ubuntu bionic/main amd64 Packages
        100 /var/lib/dpkg/status

3. Converted LUKS2 format startup Ubuntu drive should be able to add / change keys.

4. All changed/added passphases get password error at startup.

[Ubuntu Foundations Team Bug Bot (crichton)]

Thank you for taking the time to report this bug and helping to make Ubuntu better. It seems that your bug report is not filed about a specific source package though, rather it is just filed against Ubuntu in general. It is important that bug reports be filed about source packages so that people interested in the package can find the bugs about it. You can find some hints about determining what package your bug might be about at https://wiki.ubuntu.com/Bugs/FindRightPackage. You might also ask for help in the #ubuntu-bugs irc channel on Freenode.

To change the source package that this bug is filed about visit https://bugs.launchpad.net/ubuntu/+bug/1755959/+editstatus and add the package name in the text box next to the word Package.

[This is an automated message. I apologize if it reached you inappropriately; please just reply to this message indicating so.]

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.