View button after Ubmit from oracle page Apex

Question

I have a test page on https://apex.oracle.com/pls/apex/f?p=43921:2 user test password test, which already working ok, in general. It migrates employees using a shuttle object, and using Collections to update information. So far so good. It turns out that I don’t want to leave enabled, or display the migration button, when I remove all items from the collection, which are fed on the shuttle. In the shuttle to each change I feedback to Collection and at the end I reset it, knowing that if there is at least one record of this Collection there will be at least one seq_id equal to 1. I created a little validation like this:

declare
vazio NUMBER;
begin
select 1 into vazio from dual 
INTERSECT
select seq_id  from apex_collections col where collection_name = 'COLECAO_POSTOS_EMPREGADOS'; 

    if vazio  = 1 then
        RETURN TRUE;
    END IF;    
    EXCEPTION WHEN NO_DATA_FOUND THEN
       RETURN FALSE;
end;

I added a Dynamic action in the changing of the running shuttle, which makes a submitt page, when returning true this condition. And I created a server-side-condition on the migration button. Only when I press the shuttle the button is not displayed. Since Submit has this function of giving the server new client information, I don’t understand why the button was not displayed. I guess my attempt was a little too far-fetched, too. Does anyone have any other solution how to show/hide or enable/disable the button, with SHUTTLE features?

Thank you