Hi Aijaz,

Which plugin are you using to add a variation gallery?

You can try our plugin here: https://wordpress.org/plugins/wpc-additional-variation-images/. It's compatible with WPC Variation Bulk Editor.

Please send me your website credentials (wp-admin link, username, and password) or create a dev/staging site with identical configurations so I can check for any issues.

I've added a snippet for you. Please recheck it.

// WPC Variation Bulk Editor - Fix for gallery images
add_action( 'wpcvb_bulk_update_variation', function ( $variation_id, $fields ) {
	if ( ! empty( $fields['wd_additional_variation_images'] ) ) {
		update_post_meta( $variation_id, 'wd_additional_variation_images_data', sanitize_text_field( $fields['wd_additional_variation_images'] ) );
	} elseif ( ! empty( $fields['woodmart_variation_gallery'] ) ) {
		update_post_meta( $variation_id, 'wd_additional_variation_images_data', sanitize_text_field( $fields['woodmart_variation_gallery'] ) );
	}
}, 99, 2 );