I am using my own host and have done exactly (I think) what you are suggesting. I get the new password which works to get into this forum, but it rejects it when I try to log into my url/wp-login.php.
The username I use to attempt is the U/N I use in the request.
Note however, when I use the e mail which is the one I thought I put in the records and the one the PW is sent to, for the U/N, it says no such e mail exists in the system.