Basic Password Reset steps not working I have reviewed other similar posts, but none matches my problem.

I built a Drupal site based on an old ASP.NET site. I imported the users from the old DB (which had passwords in plain text!). Most users have been able to log in fine, using their old username (email addresses) and passwords.

But a few users are having trouble logging in. In some cases they forgot their password from the old site.

So they request a new password on the login page, get the email with the one-time login link, use it to change their password, but they can't login again using the new password.

What I have done to test / fix


tried resetting password myself in a testing account I set up a couple months ago:


got reset password email link
made sure I was logged out on the site
user emailed link  to get into the account
entered new password
logged out and then couldn't log in again with the password I just entered ("Sorry, unrecognized username or password. Have you forgotten your password?")

tried using a different browser, flushed cookies and cache, all to no avail. I cannot seem to login to this account EXCEPT by requesting a password reset email and using the link in that. But if I log out, I cannot log in again.
installed Password Reset Landing Page (https://www.drupal.org/project/prlp). This moved the password resetting to the page you land on from the email link, but it didn't solve the problem.
I also just tried making a different brand new testing account, asking for a password reset, resetting as before. This time it worked. No idea why it works with this new account but not with the other, older testing account. To be clear, the old testing account still doesn't work following the same steps that worked for the new account.
I monitored the user table in the DB. The password is being changed, but system doesn't recognize the newly entered password.


Is there anything I can post here to get help investigating this?
Tried to reproduce this but wasn't able to make it. Below is my process.

no prlp module


created new user with notify email
used onetime login link
changed password
logged out
logged in using the new password. SUCCESS


with prlp module


request new password
used onetime login link
changed password in the one time login page. SUCCESS
logged out
logged in using the new password

5.1. using username 'asd'. SUCCESS

5.2. using email 'asd@asd.com'. FAIL (not relevant)


enabled logintoboggan (to use email as login)


login using email and new password. SUCCESS
logout
request new password
used one time login link
changed password in the one time login page. SUCCESS
logged out
logged in using the new password

7.1. using username 'asd'. SUCCESS

7.2. using email 'asd@asd.com'. SUCCESS


Anything you'd like to add or to test?