SnapCenter Plugin for MySQL failing to authenticate

I'm running SnapCenter 4.3.1 with MySQL plugin 2.0. Setting up two servers, both CentOS 7.8 with MySQL CE 8.0 set to store their data in a folder mounted off a filer using NFSv4. One is working, but the other is throwing me this error when I try to unlock the instance:

I found this KB article: https://mysupport.netapp.com/site/article?lang=en&type=solution&page=%2FAdvice_and_Troubleshooting%2FData_Protection_and_Security%2FSnapCenter%2FSnapCenter_MySQL_Plugin_configure_credentials_Fatal_error:_Failed_to_authenticate_all_MySQL_instances

However, when I drop the user and re-add it using the referenced commands, I get a number of errors:

mysql> CREATE USER 'snapcenter'@'%' IDENTIFIED BY '<plaintextpassword>';
Query OK, 0 rows affected (0.01 sec)

mysql> GRANT ALL PRIVILEGES ON *.* TO 'snapcenter'@'%' WITH GRANT OPTION;
Query OK, 0 rows affected (0.01 sec)

mysql> GRANT ALL PRIVILEGES ON *.* TO 'snapcenter'@'localhost';
ERROR 1410 (42000): You are not allowed to create a user with GRANT
mysql> GRANT ALL PRIVILEGES ON *.* TO 'snapcenter'@'%';
Query OK, 0 rows affected (0.01 sec)

mysql> ALTER USER 'snapcenter'@'localhost' IDENTIFIED WITH mysql_native_password BY '<plaintextpassword>';
ERROR 1396 (HY000): Operation ALTER USER failed for 'snapcenter'@'localhost'
mysql> FLUSH PRIVILEGES;
Query OK, 0 rows affected (0.01 sec)

I'm not very familiar with MySQL, so I'm not sure what I'm doing wrong here...