Why does the list open with two clicks?

Question

css

Why does the list open with two clicks? Everything was fine, but at some point the list began to open with two clicks.

<div class="dropdown">
  <button class="btn btn-secondary dropdown-toggle" type="button" id="dropdownMenuButton" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
    Кнопка выпадающего списка
  </button>
  <div class="dropdown-menu" aria-labelledby="dropdownMenuButton">
    <a class="dropdown-item" href="#">Action</a>
    <a class="dropdown-item" href="#">Another action</a>
    <a class="dropdown-item" href="#">Something else here</a>
  </div>
</div>

Can anyone come across this?

Answer 1

There is not enough input, maybe it is there in which container it is stuffed or something like that.
On a bare example, everything works as it should, of course:
https://jsfiddle.net/bsncz4dt/