Build completes succesfully, image names are displayed, but after click on it - nothing happens. My code:

ViewController.swift:

import UIKit

class ViewController: UITableViewController {
    var pictures = [String]()

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view.

        let fm = FileManager.default
        let path = Bundle.main.resourcePath!
        let items = try! fm.contentsOfDirectory(atPath: path)

        for item in items {
            if item.hasPrefix("nssl") {
                pictures.append(item)
            }
        }

        print(pictures)
    }

    override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return pictures.count
    }

    override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let cell = tableView.dequeueReusableCell(withIdentifier: "Picture", for: indexPath)
        cell.textLabel?.text = pictures[indexPath.row]
        return cell
    }

    override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
        if let vc = storyboard?.instantiateViewController(withIdentifier: "Detail") as? DetailViewController {
            vc.selectedImage = pictures[indexPath.row]
            navigationController?.pushViewController(vc, animated: true)
        }
    }

}

DetailViewController:

import UIKit

class DetailViewController: UIViewController {

    @IBOutlet var imageView: UIImageView!

    var selectedImage: String?

    override func viewDidLoad() {
        super.viewDidLoad()

        if let imageToLoad = selectedImage {
            imageView.image = UIImage(named:imageToLoad)
        }
    }

Detail View Controller Scene has assigned custom class DetailViewController, Storyboard ID "Detail".

Builtime warning: warning: Unsupported Configuration: “Navigation Controller“ is unreachable because it has no entry points, and no identifier for runtime access via -[UIStoryboard instantiateViewControllerWithIdentifier:].

P.S. DetailViewController.swift file in project library is dimmed compared to other files. Not sure if that is relevant.

I'm still stuck with this problem

I tried @gumlooter's advice, I tried clearing Derived Data, restarting Xcode... no luck.

Using Xcode 13.2 beta 2 (13C5081f)

So I installed the latest/stable Xcode 13.1 and opened Project1 in it and the problem went away. Doing this also fixed the problem in Xcode 13.2 beta 2 :)