will be expecting your feed back sir.

thanks

I just tested the code but it did not work, the current logged in user is still the post author instead of the assigned anonymous user.

YES im sure the anonymous user ID exists.

1. workflow setting = on submission – publish post
2. I also have a custom post taxonomy called (locations)
3. redirect user to = Yes, to the single post screen.
4. im also using the shortcode [bbl-create-by-post-type post_type=’post’] in the (create-new-post) page
5. I also have buddyblog pay per post active

This is all the buddyblog code I have I dont think there should be any conflict

 // Request confirmation before post submission.
add_filter( 'bblpro_submission_button_classes', function ( $classes ) {
	array_push( $classes, 'bbl-confirm-action' );

	return $classes;
} );

// Buddyblog minimum words for publishing
add_filter( 'bblpro_validation_errors', function ( $errors, $data ) {

	if ( $errors->has_errors() ) {
		return $errors;
	}
	$content     = empty( $data['bbl_post_content'] ) ? '' : $data['bbl_post_content'];
	$words_count = (int) str_word_count( $content );

	if ( $words_count < 100 ) {
		$errors->add( 'bbl_post_content', _x( 'A minimum of 100 words is required to publish.', 'Post form validation message', 'buddyblog-pro' ) );
	}
	return $errors;
}, 10, 2 );

/**
 * Assign (Sponsored Post) category to BuddyBlog pay per post articles on checkout.
 */
add_action( 'bblpro_ppp_post_published', function( $post_id ) {
	$post_type = get_post_type( $post_id );
	if ( 'post' != $post_type ) {
		return;
	}
	// Get category.
	$newcat = get_term_by( 'name', 'Sponsored posts', 'category' );
	if ( ! $newcat ) {
		return;
	}
	wp_set_post_categories( $post_id, $newcat->term_id, true );
} );

/**
 * Update BuddyBlog Author when a post is submitted in a specific category.
 */
add_filter( 'bblpro_post_submission_prepared_data', function ( $post_data, $form_id, $post, $is_submission ) {
	// update author if the category was selected. Don't do anything on edit.

    $anonymous_cat_id = 1487;
    $anonymous_user_id = 4766806;

    if( ! $is_submission ) {
        return $post_data;
    }

	$selected_terms_ids = isset( $post_data['tax_input'] ) ? (array) $post_data['tax_input'] : array();

	$selected_categories = isset( $selected_terms_ids['category'] ) ? (array) $selected_terms_ids['category']: array();

    if( ! $selected_categories  || ! in_array( $anonymous_cat_id, $selected_categories ) ) {
        return $post_data;
    }

	// Update.
	$post_data['post_author'] = $anonymous_user_id;
	// keep current user data for future?
	if ( ! empty( $post_data['ID'] ) ) {
		update_post_meta( $post_data['ID'], '_bbl_original_post_author', get_current_user_id() );
	}

	return $post_data;
}, 10, 4 );