MySQL GROUP BY acting strange, not returning expected result

I'm trying to return the row with ID 258776, here's what I've tried so far...

Without GROUP BY:

SELECT main.id, main.message_id, main.inbox_id, main.uid, main.body, main.created_at FROM (
                SELECT i.id as inbox_id, i.message_id, msg.* FROM inbox AS i
                INNER JOIN message AS msg ON i.message_id = msg.id
                WHERE i.profile_id = 2135
                AND i.is_sent = 0
                AND i.is_deleted = 0
                AND msg.uid = '570cc3a568402'
                ORDER BY msg.updated_at DESC
            ) AS main #GROUP BY main.uid


= ID =  =MSG =  =INB =  = UID       =   = BD =   = CREATED         =  
258776  258776  524785  570cc3a568402   wtf      2016-06-22 11:34:29  
217149  217149  438907  570cc3a568402   <br />   2016-04-12 11:45:09  

Try with GROUP BY

SELECT main.id, main.message_id, main.inbox_id, main.uid, main.body, main.created_at FROM (
                SELECT i.id as inbox_id, i.message_id, msg.* FROM inbox AS i
                INNER JOIN message AS msg ON i.message_id = msg.id
                WHERE i.profile_id = 2135
                AND i.is_sent = 0
                AND i.is_deleted = 0
                AND msg.uid = '570cc3a568402'
                ORDER BY msg.updated_at DESC
            ) AS main GROUP BY main.uid

= ID =  =MSG =  =INB =  = UID       =   = BD =   = CREATED         =  
217149  217149  438907  570cc3a568402   <br />   2016-04-12 11:45:09  

Switch to ASC but GROUP BY gives same results ?

SELECT main.id, main.message_id, main.inbox_id, main.uid, main.body, main.created_at FROM (
                SELECT i.id as inbox_id, i.message_id, msg.* FROM inbox AS i
                INNER JOIN message AS msg ON i.message_id = msg.id
                WHERE i.profile_id = 2135
                AND i.is_sent = 0
                AND i.is_deleted = 0
                AND msg.uid = '570cc3a568402'
                ORDER BY msg.updated_at ASC
            ) AS main GROUP BY main.uid

= ID =  =MSG =  =INB =  = UID       =   = BD =   = CREATED         =  
217149  217149  438907  570cc3a568402   <br />   2016-04-12 11:45:09

I presume it should work fine if I didn't need to use an INNER join ? :(