order by not working on group by same samity_id and staff_id

Question

I have 5 tables. I want latest staff name only. In order to better understand, I mentioned all the information in the table. If anyone has a problem with understanding or if you have any information, please comment.

Please read the whole and follow the information given at the bottom of the page.

Table 1: samities

+-----------+------------------------+-----------+--------+---------+---------+------------+---------+--------+---------------------+
| samity_id | name                   | office_id | day_id | code    | gend_id | open_date  | user_id | status | create_at           |
+-----------+------------------------+-----------+--------+---------+---------+------------+---------+--------+---------------------+
|         1 | Torofmeru Park MS      |         1 |      3 | 001-001 |       2 | 2022-03-14 |       2 |      1 | 2022-03-14 16:36:13 |
|         2 | Gabtoli Master Para MS |         1 |      6 | 001-002 |       2 | 2022-03-16 |       2 |      1 | 2022-03-16 14:43:40 |
+-----------+------------------------+-----------+--------+---------+---------+------------+---------+--------+---------------------+

Table 2: samity_assignment

+----------+----------+-----------+-----------+---------+--------+-----------+
| sasgn_id | staff_id | samity_id | office_id | user_id | status | create_at |
+----------+----------+-----------+-----------+---------+--------+-----------+
|        1 |        1 |         1 |         1 |       2 |      1 | NULL      |
|        2 |        2 |         1 |         1 |       2 |      1 | NULL      |
+----------+----------+-----------+-----------+---------+--------+-----------+

Table 3: employees

+----------+-------------+------+-----------+--------+
| staff_id | name        | code | office_id | status |
+----------+-------------+------+-----------+--------+
|        1 | Staff Mr. A |    1 |         1 |      1 |
|        2 | Staff Mr. B |    2 |         2 |      1 |
+----------+-------------+------+-----------+--------+

Table 4: samity_days

+--------+-------------+--------------+--------+
| day_id | define_long | define_short | status |
+--------+-------------+--------------+--------+
|      1 | Saturday    | Sat          |      1 |
|      2 | Sunday      | Sun          |      1 |
|      3 | Monday      | Mon          |      1 |
|      4 | Tuesday     | Tue          |      1 |
|      5 | Wednesday   | Wed          |      1 |
|      6 | Thursday    | Thu          |      1 |
|      7 | Friday      | Fri          |      2 |
+--------+-------------+--------------+--------+

Table 5: genders

+---------+-------------+--------------+--------+
| gend_id | define_long | define_short | status |
+---------+-------------+--------------+--------+
|       1 | Male        | M            |      1 |
|       2 | Female      | F            |      1 |
|       3 | Others      | O            |      1 |
+---------+-------------+--------------+--------+

My Query:

SELECT
    `sam`.`samity_id` `id`,
    `sam`.`name`,
    `sam`.`code`,
    `emp`.`name` `staff_name`,
    `day`.`define_short` `day_name`,
    `gen`.`define_long` `gender_name`,
    `sam`.`open_date` `opening`,
    `sam`.`status`,
    ( SELECT COUNT( saa.sasgn_id ) FROM samity_assignment saa WHERE sam.samity_id = saa.samity_id ) member_total,
    `saa`.`sasgn_id` `samity_assingment_id` 
FROM
    `samities` `sam`
    LEFT JOIN `samity_assignment` `saa` ON `saa`.`samity_id` = `sam`.`samity_id`
    LEFT JOIN `employees` `emp` ON `saa`.`staff_id` = `emp`.`staff_id`
    LEFT JOIN `samity_days` `day` ON `sam`.`day_id` = `day`.`day_id`
    LEFT JOIN `genders` `gen` ON `sam`.`gend_id` = `gen`.`gend_id` 
GROUP BY
    `saa`.`samity_id` 
ORDER BY
    `sam`.`name` ASC,
    `saa`.`sasgn_id` DESC 
    LIMIT 25

Current Result:

Array
(
    [0] => stdClass Object
        (
            [id] => 2
            [name] => Gabtoli Master Para MS
            [code] => 001-002
            [staff_name] => 
            [day_name] => Thu
            [gender_name] => Female
            [opening] => 2022-03-16
            [status] => 1
            [member_total] => 0
            [samity_assingment_id] => 
        )

    [1] => stdClass Object
        (
            [id] => 1
            [name] => Torofmeru Park MS
            [code] => 001-001
            [staff_name] => Staff Mr. A
            [day_name] => Mon
            [gender_name] => Female
            [opening] => 2022-03-14
            [status] => 1
            [member_total] => 2
            [samity_assingment_id] => 1
        )
)

I want:

Array
(
    [0] => stdClass Object
        (
            [id] => 2
            [name] => Gabtoli Master Para MS
            [code] => 001-002
            [staff_name] => 
            [day_name] => Thu
            [gender_name] => Female
            [opening] => 2022-03-16
            [status] => 1
            [member_total] => 0
            [samity_assingment_id] => 
        )

    [1] => stdClass Object
        (
            [id] => 1
            [name] => Torofmeru Park MS
            [code] => 001-001
            [staff_name] => Staff Mr. B
            [day_name] => Mon
            [gender_name] => Female
            [opening] => 2022-03-14
            [status] => 1
            [member_total] => 2
            [samity_assingment_id] => 1
        )
)

There are two staff_id in the same samity_id. I just want to have the latest staff_id. I hope someone will help me.