You need to remember two things whenever you are going to implement pagination in Codeigniter:
First thing Configuration related to page generation which is actually:
// Loads pagination library
$this->load->library('pagination');
// @params $url = your controller + method path
$config['base_url'] = base_url() . $url;
// @params $totalRows = Total result found in query
$config['total_rows'] = $totalRows;
// @params $perPage = In your case it is 50
$config['per_page'] = $perPage;
// @params $segment = This is what you are missing in your code. Segment is the factor from where system reads which page records need to be shown
$config['uri_segment'] = $segment;
$this->pagination->initialize($config);
Second Thing Pagination configuration related to designing part:
$config['full_tag_open'] = '<ul class="pagination pagination-sm m-t-none m-b-none">';
$config['full_tag_close'] = '</ul>';
$config['prev_link'] = '<i class="fa fa-chevron-left"></i>';
$config['prev_tag_open'] = '<li>';
$config['prev_tag_close'] = '</li>';
$config['next_link'] = '<i class="fa fa-chevron-right"></i>';
$config['next_tag_open'] = '<li>';
$config['next_tag_close'] = '</li>';
$config['cur_tag_open'] = '<li class="active"><a href="#">';
$config['cur_tag_close'] = '</a></li>';
$config['num_tag_open'] = '<li>';
$config['num_tag_close'] = '</li>';
$config['first_tag_open'] = '<li>';
$config['first_tag_close'] = '</li>';
$config['last_tag_open'] = '<li>';
$config['last_tag_close'] = '</li>';
$config['first_link'] = '<i class="fa fa-chevron-left"></i> <i class="fa fa-chevron-left"></i>';
$config['last_link'] = '<i class="fa fa-chevron-right"></i><i class="fa fa-chevron-right"></i>';
$this->pagination->create_links();
This is the running script which I have been using in my projects. Working fine. You need to check uri_segment you are passing during initialization.
Let me know if you face any issue.