Featured image upload option not working properly?

I’m trying to make a new plugin. I hope it’s maxim complete. but now I face a problem. When install my custom plugin then the Featured image upload option not working properly. It’s show like a media uploaded https://postimg.org/image/und4s6tdz/ not show like https://postimg.org/image/g5fxk722v/ .

My custom plugin code give blow .

<?php

/*
Plugin Name: ABS Gallery
Plugin URI: https://www.absiddik.net/
Description: This plugin will enable accordion in your wordpress theme. You can embed accordion via shortcode in everywhere you want, even in theme files.
Author: AB Siddik
Version: 1.0.0
Author URI: https://www.absiddik.net/
*/

/*
 *Latest Jquery For ABS Gallery Plugin.
 */
function abs_gallary_latest_jquery() {
    wp_enqueue_script( 'jquery' );
}
add_action( 'init', 'abs_gallary_latest_jquery' );

/**
 * Main Jquery and Style for ABS Gallery Plugin,
 */
function abs_gallery_main_jquery() {

	wp_enqueue_script( 'abs-gallery-boortstrao-js','//maxcdn.bootstrapcdn.com/bootstrap/3.3.4/js/bootstrap.min.js', array('jquery'), 1.0, false);

	wp_enqueue_script( 'abs-gallery-js', plugins_url( '/js/slick.min.js', __FILE__ ), array('jquery'), 1.0, false);

	wp_enqueue_script( 'abs-gallery-active-js', plugins_url( '/js/active.js', __FILE__ ), array('jquery'), 1.0, false);

	wp_enqueue_style( 'abs-gallery-css', plugins_url( '/css/slick.css', __FILE__ ));

	wp_enqueue_style( 'abs-gallery-theme-css', plugins_url( '/css/slick-theme.css', __FILE__ ));

	wp_enqueue_style( 'abs-prefix-font-awesome', '//maxcdn.bootstrapcdn.com/bootstrap/3.3.4/css/bootstrap.min.css', array(), '3.3.4' );

	wp_enqueue_style( 'abs-gallery-main-css', plugins_url( '/css/gallery-plu.css', __FILE__ ));
}

add_action( 'init', 'abs_gallery_main_jquery' );

/*===== Thumbonial Support for ABS gallery plugin =====*/
add_theme_support( 'post-thumbnails' );

add_image_size( 'img_slide',400,400, true );

add_image_size( 'img_thum',75,75, true );

include_once('inc/quate-form.php');

/* This sortcode use for Tab Titel */
function abs_gallery_slide($atts){
	extract( shortcode_atts( array(
		'catagory' => '',
	), $atts, 'gallery' ) );

    $q = new WP_Query(
        array('posts_per_page' => -1,'post_type'=> 'absgallery', 'gallery_cat' => $catagory));		

	$list = '<div class="slider-for">';
	while($q->have_posts()) : $q->the_post();

	$img_slide = wp_get_attachment_image_src( get_post_thumbnail_id( $post->ID ), 'img_slide' );

		$list .= '
					<div class="pro_slide">
						<div class="pro_info">
							<h2>'.get_the_title().'</h2>
							<p>'.get_the_content().'</p>
							<p class="onclick">Popup</p>
						</div>
						<div class="pro_img">
							<img src="'.$img_slide[0].'" alt="" />
						</div>

					</div>
				';
	endwhile;
	$list.= '</div>';
	wp_reset_query();
	return $list;
}
add_shortcode('galslide', 'abs_gallery_slide');

/* This sortcode use for Tab Content */
function abs_gallery_thum($atts){
	extract( shortcode_atts( array(
		'catagory' => '',
	), $atts, 'gallery' ) );

    $q = new WP_Query(
        array('posts_per_page' => -1,'post_type'=> 'absgallery', 'gallery_cat' => $catagory));		

	$list = '<div id="adding" class="slider-nav">';
	while($q->have_posts()) : $q->the_post();
		$img_thum = wp_get_attachment_image_src( get_post_thumbnail_id( $post->ID ), 'img_thum' );

		$list .= '
		<div class="pro_thum">
			<img src="'.$img_thum[0].'" alt="" />
		</div>
		';
	endwhile;
	$list.= '</div>';
	wp_reset_query();
	return $list;
}
add_shortcode('galthum', 'abs_gallery_thum');

/****Main galary *****/

function abs_gallery_main($atts){
	  $a = shortcode_atts( array(
        'catagory' => '',
    ), $atts );

	return'
	<div class="row">
		<div class="col-md-12">
		'.do_shortcode('[galslide catagory="'.$catagory.'"][galthum catagory="'.$catagory.'"]').'
		</div>
	</div>
	';
}
add_shortcode('abs_gallery','abs_gallery_main');

/*This custom post for ABS Gallery*/
add_action( 'init', 'abs_gallery_custom_post' );

function abs_gallery_custom_post() {
	$labels = array(
		'name'               => _x( 'Gallry Item', 'abs-gallery-plu' ),
		'singular_name'      => _x( 'Gallry Item',  'abs-gallery-plu' ),
		'menu_name'          => _x( 'Gallry Items', 'abs-gallery-plu' ),
		'name_admin_bar'     => _x( 'Gallry Item',  'abs-gallery-plu' ),
		'add_new'            => _x( 'Add New Gallry Item', 'abs-gallery-plu' ),
		'add_new_item'       => __( 'Add New Gallry Item', 'abs-gallery-plu' ),
		'new_item'           => __( 'New Gallry Items', 'abs-gallery-plu' ),
		'edit_item'          => __( 'Edit Gallry Item', 'abs-gallery-plu' ),
		'view_item'          => __( 'View Gallry Item', 'abs-gallery-plu' ),
		'all_items'          => __( 'All Gallry Items', 'abs-gallery-plu' ),
		'search_items'       => __( 'Search Gallry', 'abs-gallery-plu' ),
		'parent_item_colon'  => __( 'Parent Gallry:', 'abs-gallery-plu' ),
		'not_found'          => __( 'No Gallry Items found.', 'abs-gallery-plu' ),
		'not_found_in_trash' => __( 'No Gallry Items found in Trash.', 'abs-gallery-plu' )
	);

	$args = array(
		'labels'             => $labels,
		'public'             => true,
		'publicly_queryable' => true,
		'show_ui'            => true,
		'show_in_menu'       => true,
		'query_var'          => true,
		'rewrite'            => array( 'slug' => 'gallery-item' ),
		'capability_type'    => 'post',
		'has_archive'        => true,
		'hierarchical'       => false,
		'menu_position'      => null,
		'supports'           => array( 'title','editor','thumbnail')
	);

	register_post_type( 'absgallery', $args );
}

/* ----This Code for Woki Item Custom texonomy------*/
function abs_gallery_custom_post_taxonomy() {
	register_taxonomy(
		'gallery_cat',  //The name of the taxonomy. Name should be in slug form (must not contain capital letters or spaces).
		'absgallery',                  //post type name
		array(
			'hierarchical'          => true,
			'label'                         => 'Gallery Catagory',  //Display name
			'query_var'             => true,
			'show_admin_column'             => true,
			'rewrite'                       => array(
				'slug'                  => 'gallery-cat', // This controls the base slug that will display before each term
				'with_front'    => true // Don't display the category base before
				)
			)
	);

}
add_action( 'init', 'abs_gallery_custom_post_taxonomy'); 

?>

Anybody can help me what wrong with my code ?