Query have Null find by virtual column. Why?

[Alexandre Kalendarev]

The table have next structure:

CREATE TABLE `test` (
`emp_no` int(11) NOT NULL,
`data` json NOT NULL,
`name` varchar(30) GENERATED ALWAYS AS (json_extract(`data`,'$.first_name')) VIRTUAL,
PRIMARY KEY (`emp_no`)
)

I'm querying and mysql return the 45 rows:

SELECT `emp_no`, name FROM test
WHERE json_extract(`data`,'$.first_name')='Parto'

But, if I make query:

SELECT `emp_no`,name FROM test
WHERE name ='Parto'

I have empty set (0 row)

Why i have empty rowset?