Cannot store emoji in database

问题:

THE SITUATION:

Sorry in advance if this question has already been asked, but the solutions aren't working for me.

No matter what I try, I cannot store emoji in my database. They are saved as ????.
The only emojis that are properly saved are the ones that require only 3 bytes, like the shy face or the sun.

The actual utf8mb4 is not working.

It has been tested on both Android and Ios. With same results.

VERSIONS:

Mysql: 5.5.49
CodeIgniter: 3.0.0

THE STEPS:

1. I have modified database character set and collation properties.

   ALTER DATABASE my_database CHARACTER SET = utf8mb4 COLLATE = utf8mb4_unicode_ci

2. I have modified table character set and collation properties.

   ALTER TABLE table_name CONVERT TO CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci

3. I have set each field of the table, where possible, as Encoding: UTF-8(ut8mb4) and Collation: utf8mb4_unicode_ci

4. I have modified the database connection in the CodeIgniter app.

5. I have run the following: SET NAMES utf8mb4 COLLATE utf8mb4_unicode_ci

6. Lastly I have also tried this: REPAIR TABLE table_name; OPTIMIZE TABLE table_name;

Everything should have been setup properly but yet it doesn't work.

DATABASE SETTINGS:

This is the outcome running the following command:

`SHOW VARIABLES WHERE Variable_name LIKE 'character\_set\_%' OR Variable_name LIKE 'collation%';`

TABLE SETTINGS:

A screeshot of the table structure:

DATABASE CONNECTION:

These are the database connection settings inside database.php (note this is not the only database, there are also others that connect using utf8)

$db['my_database'] = array(
        'dsn'           => '',
        'hostname'      => PROJECT_DATABASE_HOSTNAME,
        'username'      => PROJECT_DATABASE_USERNAME,
        'password'      => PROJECT_DATABASE_PASSWORD,
        'database'      => PROJECT_DATABASE_NAME,
        'dbdriver'      => 'mysqli',
        'dbprefix'      => '',
        'pconnect'      => FALSE,
        'db_debug'      => TRUE,
        'cache_on'      => FALSE,
        'cachedir'      => '',
        'char_set'      => 'utf8mb4',
        'dbcollat'      => 'utf8mb4_unicode_ci',
        'swap_pre'      => '',
        'encrypt'       => FALSE,
        'compress'      => FALSE,
        'stricton'      => FALSE,
        'failover'      => array(),
        'save_queries'  => TRUE
    );

MY.CNF SETTINGS:

This is the whole content of the file my.cnf:

[mysqld]
default-storage-engine=MyISAM
innodb_file_per_table=1
max_allowed_packet=268435456
open_files_limit=10000
character-set-client-handshake = FALSE
character-set-server = utf8mb4
collation-server = utf8mb4_unicode_ci

[client]
default-character-set = utf8mb4

[mysql]
default-character-set = utf8mb4

THE QUESTION:

Do you know why is not working? Am I missing something?

HYPHOTESIS 1:

I am not sure, but the cause of the problem may be this:

As you can see in my.cnf character-set-server is clearly set as utf8mb4:

But after running the query in the database:

SHOW VARIABLES WHERE Variable_name LIKE 'character\_set\_%' OR Variable_name LIKE 'collation%';

The outcome is that character-set-server = latin1

Do you know why is that? Why is not actually updating?

HYPHOTESIS 2:

The application use several different databases. This one is set to utf8mb4 but all the others are set to utf8. It may be a problem even if they are separated databases?

Thank you!

EDIT:

This is the outcome of SHOW CREATE TABLE app_messages;

CREATE TABLE `app_messages` (
  `message_id` bigint(20) unsigned NOT NULL AUTO_INCREMENT,
  `project_id` bigint(20) NOT NULL,
  `sender_id` bigint(20) NOT NULL,
  `receiver_id` bigint(20) NOT NULL,
  `message` text COLLATE utf8mb4_unicode_ci,
  `timestamp` bigint(20) DEFAULT NULL,
  `is_read` enum('x','') COLLATE utf8mb4_unicode_ci DEFAULT NULL,
  PRIMARY KEY (`message_id`)
) ENGINE=InnoDB AUTO_INCREMENT=496 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci

EDIT 2:

I have run the following command:

INSERT INTO app_messages (message_id, project_id, sender_id, receiver_id, message, timestamp, is_read)
VALUES ('496','322','77','188', '