MariaDB Wrong Query result

I've a strange problem with a Query on MariaDB.

WITH mt AS (SELECT id, MAX(id), employee_id FROM hirings group BY employee_id)
                   SELECT d.*, mt.employee_id, mt.id FROM mt
                   LEFT JOIN hirings a ON a.id = mt.id
                   LEFT JOIN employees d ON d.id = mt.employee_id
                   WHERE (dischargedate IS NULL OR dischargedate > CURDATE()-1) AND company_id = 1
                   GROUP BY d.id ORDER BY surname

The query select all employees that have dischargedate valorized to NULL or dischargedate valorized with a value greater then today's date.

Until recently this query works fine, now it have started to doesn't select some records that should be selected.

But in some PC happens this and in other PC whith same DB and same query all works fine.

All PC's have Windows 10 Professional and the MariaDB version is the same.

I extracted manually (with a query) the record of employees and hirings table for comparation with the 2 databases.
The record extraced are identical and I can't find a explanation for this issue.

Example:
--> This record does not appear in the query result:

Query: SELECT * FROM employees WHERE surname=’DOE’

Result: employees (1r x 35)

------------------------------------
| id | Surname | Name |	Address | …
|----|---------|------|---------|---
| 413|	 DOE   | JOHN |	xxx	    | …
|----|---------|------|---------|---

Query: SELECT * FROM hirings WHERE employee_id = 413

Result: hirings (5r x 11)

-----------------------------------------------------------------------------------------------------------------------------------------
| id | Employee_id | WeekHour |	Level_id | Contract_id | DeadlineType |	DeadlineDate | PartTime | ChargeDate | DischargeDate | Contract |
|----|-------------|----------|----------|-------------|--------------|--------------|----------|------------|---------------|----------|
| 493|	   413	   |   40     |	    4	 |      4      |        1     |	2022-01-31   |    0     | 2021-12-20 | 2022-01-31    |	(NULL)  |
| 545|	   413	   |   40     |	    4	 |      4      |        1     |	2022-04-30   |    0     | 2022-02-01 | 2022-04-30    |	(NULL)  |
| 618|	   413	   |   40     |	    4	 |      4      |        1     |	2022-06-30   |    0     | 2022-05-01 | 2022-06-30    |	(NULL)  |
| 661|	   413	   |   40     |	    4	 |      2      |        4     |	2022-12-31   |    0     | 2022-07-01 | 2022-10-07    |  (NULL)  |
| 746|	   413	   |   40     |	    4	 |      1      |        1     |	(NULL)	     |    0     | 2022-10-10 | (NULL)	     |  (NULL)  |
|----|-------------|----------|----------|-------------|--------------|--------------|----------|------------|---------------|----------|

--> This record appear in the query result:
Query: SELECT * FROM employees WHERE surname=’STOJ’

Result: employees (1r x 35)

------------------------------------
| id | Surname | Name |	Address | …
------------------------------------
| 469|  STOJ   | MARY |	xxx	    | …
------------------------------------

Query: SELECT * FROM hirings WHERE employee_id = 469

Result: hirings (3r x 11)

-----------------------------------------------------------------------------------------------------------------------------------------
| id | Employee_id | WeekHour |	Level_id | Contract_id | DeadlineType |	DeadlineDate | PartTime | ChargeDate | DischargeDate | Contract |
-----------------------------------------------------------------------------------------------------------------------------------------
| 629|     469     |   36     |	    9    |      3      |        4     |	2022-10-31   |    0     | 2022-05-09 | 2022-10-31    |	(NULL)  |
| 761|     469     |   36     |	    2    |      2      |        1     | 2023-03-31   |    0     | 2022-11-01 | 2023-03-31    |	(NULL)  |
| 943|     469     |   36     |	    2    |      2      |        1     | 2023-10-30   |    0     | 2023-04-01 | (NULL)	     |  (NULL)  |
-----------------------------------------------------------------------------------------------------------------------------------------

I want to emphasize that this issue doesn't appears on my PC with the same database imported for tests.
In other PC's this issue was appears about two month ago without any software modification.

Looks like you mean to be doing SELECT MAX(id) as id, employee_id, not SELECT id, MAX(id), employee_id. The latter will return an arbitrary one of the id values for each employee_id (and generates an mt column named MAX(id) which you don't use).

Enabling the ONLY_FULL_GROUP_BY sql mode will prevent you from making mistakes like this. This is the default in recent mysql.

I solved replacing the old query with this:

SELECT * FROM employees d 
         WHERE EXISTS
         (SELECT 1 FROM hirings a 
          WHERE a.employee_id = d.id 
          AND (a.dischargedate IS NULL OR a.dischargedate > CURDATE()-1) 
          AND company_id = 1)
          GROUP BY d.id ORDER BY surname