Why bootstrap 4 responsive menu doesn't work at resolution less than 600px?

Question

Bootstrap

From 600px and more, it opens normally, and if it is less, then the menu button becomes not clickable at all. Maybe I overlooked something
(jQuery is included before the bootstrap)

<nav class="navbar navbar-expand-lg navbar-light bg-white">
                    <a class="navbar-brand" href="#">
                        <div class="logo">HELYFLY</div>
                    </a>
                    <a class="town_hidden" href="#">Москва</a>
                    <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarNavDropdown"
                        aria-controls="navbarNavDropdown" aria-expanded="false" aria-label="Toggle navigation">
                        <img src="Фигура 679.svg" alt="menu_icon" style="width: 18px;">
                    </button>
                    <div id="navbarNavDropdown" class="navbar-collapse collapse">
                        <ul class="navbar-nav mr-auto">
                            <li class="nav-item">
                                <a class="nav-link" href="#">Телефон:</a>
                            </li>
                            <li class="nav-item active">
                                <a class="nav-link" href="#"> 8(800)-123-12-12 <span
                                        class="sr-only">(current)</span></a>
                            </li>
                        </ul>

                    </div>
                </nav>