Keychain does not store generated password

At work we are using Office365.com (for some strange reason...). Every now and then the password for this site needs to be reset and I always miss the deadline for this. Often I need to ask our Admin to give me a temporary password in order to login to change password into someting else.

So today I received a temp password from Admin. I used this to login to office365.com. I was asked by Keychain if I wanted to update Keychain with this temp password. I accepted.

I then changed the password in office365 and Safari auto generated a password stating that this password should be stored in Keychain. I accepted this auto generated password.

I then logged out of office365 and tried to log back in again. Does not work.

I check what password Keychain in Safari has stored and it turns out that it only stored the temporary password, not the auto generated one.

I tried this operation twice with the same result.

What am I doing wrong?