If you encounter an issue where a user changed their password recently and they cannot login to their computer encryption system then do the following actions when logged in as an administrator:

Open the Terminal application (click the magnifying glass in the top right and type in terminal).

Remove the account first from Filevault using this command:
sudo fdesetup remove -user <UFNET USERNAME>

Type in the administrator password

Log out and log back in as admin.

Open System Preferences > Privacy & Security > scroll down to "Filevault" > Click Enable Users... > put in the Administrator password > Have the user put in their password > Click ok.

Restart and have the user try to login again.

Re-add the account using this command:
sudo fdesetup add -usertoadd <UFNET USERNAME>

Hit enter, and type the following for the prompts:

Enter the user name: administrator
Enter the password for user 'administrator': <ADMINISTRATOR PASSWORD>
Enter the password for the added user '<UFNET USERNAME>': <UFNET PASSWORD>

Restart the computer and have the user try to login again.