For file uploads to occur, the forms encoding type needds to be set to multipart/form-data.
change the form tag:
<form action="menus_Update.php?ID=<?php echo(rawurlencode($row_WADAmenus['ID'])); ?>" method="post" name="WADAUpdateForm" id="WADAUpdateForm">
to:
<form action="menus_Update.php?ID=<?php echo(rawurlencode($row_WADAmenus['ID'])); ?>" method="post" enctype="multipart/form-data" name="WADAUpdateForm" id="WADAUpdateForm">