Dropdown with left join

With the settings in the image, I could not display the field "name" in the dropdown, in this case how should I proceed?

The "user_id" field is listed normally.

In the "uGer" model I make a left join with the joomla users table, because I need to get the username
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If you look at the debug, is it actually retrieving the name at all?

with the above setting (return an array of key / value pairs) I can only get the return from user_id (Ger.user_id), but if I change to (All matching records) I can get the return of names (uGer.name) too .
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[read_managers] => Array
        (
            [log] => Array
                (
                    [0] => SELECT `Ger`.`user_id` AS `Ger.user_id` FROM `e3nd_a_managers` AS `Ger` LIMIT 100;
                )

            [var] => Array
                (
                    [930] => 930
                    [931] => 931
                )

        )

retrieve it as
​
Ger.userid:Ger.id
uGer.name:Ger.name

I was able to solve by changing the main db for users, and changing some options of the field (where conditions).