Executing a stored procedure with cursor in PHP

I have a stored procedure that I am trying to call from my php. Here is the stored procedure:

BEGIN
DECLARE done INT DEFAULT FALSE;
declare phone_temp VARCHAR(20) default '';
declare phone_cur cursor for SELECT DISTINCT sentNum FROM Queue;
declare continue handler for not found set done = true;

#create temp table
create temporary table if not exists temp_return AS SELECT * FROM Queue LIMIT 0;
#empty if exists
delete from temp_return;

open phone_cur;

phone_loop: LOOP
    fetch phone_cur into phone_temp;
    if done then
        leave phone_loop;
    end if;

   insert into temp_return SELECT * FROM Queue WHERE num2=phone_temp LIMIT 2;
   insert into temp_return SELECT * FROM Queue WHERE num1=phone_temp LIMIT 1;
end loop phone_loop;
close phone_cur;

select * from temp_return;

drop table if exists temp_return;
END

Directly in mysql workbench, calling it works. In php, it does not work. Here is my php:

function grabFromSmsQueue(){
    global $myStmt, $conn;
    if(isset($myStmt)){
        $myStmt -> execute();
    }
    else{
        $query = "CALL myStoredProc();";
        $myStmt = $conn->stmt_init();
        $myStmt -> prepare($query);
        $myStmt -> execute();

    }
    $result = $myStmt -> get_result();
    //print_r ($result);
    $info = [];
    if(isset($result)){
        while($data = $result->fetch_assoc()){
            $info[] = $data;
        }
    }
    return $info;
}

Connecting like this, I get the following error

The localhost page isn’t working
localhost didn’t send any data.
ERR_EMPTY_RESPONSE

I traced my problem back to an issue with $data = $result->fetch_assoc(), because when I comment that out and put in the print_r I get something actually returned, which is mysqli_result Object ( [current_field] => 0 [field_count] => 9 [lengths] => [num_rows] => 0 [type] => 1 ). I have drawn the conclusion that it is not working because [num_rows] => 0.

Now, going back to my stored procedure, I took out all mentions of a cursor and replaced it with a hard-coded value, and it worked in both workbench and php. I have already verified that the user connecting through php has permission, that the connection is open, and that the same code can execute other stored procedures (ones that do not include cursors). Does this mean that I can not use cursors in stored procedures that are being called by php? Are there alternatives to cursors? Am I missing something in my php syntax to deal with cursors?

Drew

Based on discussions in chat for 3 groupings, and this provided SQLFiddle for test data (not much data there).

Due to testing data with a sliding window of where now() is in relation to that data, the following variable was used to "freeze" now(). Simply to facilitate testing and verification of output.

So, ditch that ultimately and change the 4 references in the code that use it (note that Group 3 uses it twice).

The now() variable:

select @theNow:=now();
-- REM OUT the following line. It is used only for testing (as now will chg, your data won't)
select @theNow:='2016-06-23 14:00:00';

The Query:

select id,sentNum,message,sentTime,startAtTime,sentByTime,msgType,theGrp from
(   select id,sentNum,message,sentTime,startAtTime,sentByTime,msgType,theGrp,
    if(sentNum!=@lastSentNum,greatest(@sentNumChg:=1,0),least(@sentNumChg:=0,1)) as dummy1,
    if(theGrp!=@lastGrp,greatest(@grpChg:=1,0),least(@grpChg:=0,1)) as dummy2,
    if(@sentNumChg=1 or @grpChg=1,@seqNum:=1,@seqNum:=@seqNum+1) as seqNum,
    @lastSentNum:=sentNum as setLast01,
    @lastGrp:=theGrp as setLast02
    from
    (   -- GROUP 1: sentByTime<=now(), INVITE
        select `id`, `sentNum`, `message`, `sentTime`, `startAtTime`, `sentByTime`, `msgType`, 1 as theGrp
        from SmsQueue
        where sentByTime<=@theNow and msgType='invite'
        UNION ALL
        -- GROUP 2 startAtTime<=now(), BROADCAST
        select `id`, `sentNum`, `message`, `sentTime`, `startAtTime`, `sentByTime`, `msgType`, 2 as theGrp
        from SmsQueue
        where startAtTime<=@theNow and msgType='broadcast'
        UNION ALL
        -- GROUP 3: sentByTime>now() && startAtTime<=now(), INVITE
        select `id`, `sentNum`, `message`, `sentTime`, `startAtTime`, `sentByTime`, `msgType`, 3 as theGrp
        from SmsQueue
        where sentByTime>@theNow and startAtTime<=@theNow and msgType='invite'
    ) d1
    cross join (select @sentNumChg:=0,@grpChg:=0,@lastSentNum:='',@lastGrp:=0,@seqNum:=0) as xParams
    order by sentNum,theGrp,sentByTime,id -- id is the tie-break
) d2
where (theGrp=1 and seqNum<3) or (theGrp=2 and seqNum=1) or (theGrp=3 and seqNum=1)
order by sentNum,theGrp;

Output (my client tool is text challenged at the moment):