Index: includes/class-wp-posts-list-table.php
--- includes/class-wp-posts-list-table.php Base (BASE)
+++ includes/class-wp-posts-list-table.php Locally Modified (Based On LOCAL)
@@ -212,11 +212,11 @@
 			if ( is_object_in_taxonomy( $post_type, 'category' ) ) {
 				$dropdown_options = array(
 					'show_option_all' => __( 'View all categories' ),
-					'hide_empty' => 0,
-					'hierarchical' => 1,
-					'show_count' => 0,
-					'orderby' => 'name',
-					'selected' => $cat
+					'hide_empty'      => 0,
+					'hierarchical'    => 1,
+					'show_count'      => 0,
+					'orderby'         => 'name',
+					'selected'        => (int) $cat
 				);
 				wp_dropdown_categories( $dropdown_options );
 			}