HashRouter URL is updated on click but component not (blocking updates) - reactjs

Question

I've created an app via create-react-app. I want to use the HashRouter functionality for my app (React Router v4), but it is not working as expected.
Actually I don't know why. I.e. when I click on the contact link, then the URL changes to the route /contacts, but the related component is not being showed. It still shows the previous loaded component. The links are placed in the Navigation component. Here is one example of a Link.
<Link key={"navigation" + bu.name + "Key"}
to="/products"
className="nav-link dropdown-item imageLink animated"
onClick={(e) => this.handleClickBU(e, bu.bu)}>{bu.name}
</Link>
This is my code of App.js:
import React, { Component } from "react";
import {
BrowserRouter as Router,
HashRouter,
Route,
Link,
Switch
} from "react-router-dom";
<HashRouter>
<div>
<Background />
<div id="wrap">
<div id="main" className="container clear-top marginBottom50px main">
<div id="content">
<Navigation
key="navBar"
languagesToShow={this.state.languagesToShow}
currentLanguage={this.state.currentLanguage}
onLanguageChange={this.handleLanguageChange.bind(this)}
onBUChange={this.handleBUChange.bind(this)}
onIndustryChange={this.handleIndustryChange.bind(this)}
onCountryChange={this.handleCountryChange.bind(this)}
/>
<Route
key={"mainPageRoute"}
path={"/"}
exact={true}
render={(routeProps) => (
<MainPage
{...routeProps}
currentLanguage={this.state.currentLanguage}
country={this.state.countryObject}
contacts={this.state.contacts}
onCountryChange={this.handleCountryChange.bind(this)}
/>
)}
/>
<Route
key={"contactRoute"}
path={"/contact"}
exact={true}
render={(routeProps) => (
<ContactList
{...routeProps}
showCountrySelection={true}
currentLanguage={this.state.currentLanguage}
country={this.state.countryObject}
contacts={this.state.contacts}
onCountryChange={this.handleCountryChange.bind(this)}
key={"contactList"}
/>
)}
/>
<Route
key={"productsRoute"}
path={"/products"}
exact={true}
render={(routeProps) => (
<Products
{...routeProps}
ref={this.props.innerRef}
key="products"
isLoading={this.state.isLoading}
country={this.state.countryObject}
currentLanguage={this.state.currentLanguage}
currentBU={this.state.currentBU}
showMainProductGroups={this.state.showMainProductGroups}
showMainProductGroupDetails={
this.state.showMainProductGroupDetails
}
showProductGroupDetails={this.state.showProductGroupDetails}
mainProductGroups={this.state.mainProductGroups}
onShowMainProductGroupDetailsChange={this.handleShowMainProductGroupDetailsChange.bind(
this
)}
onShowProductGroupDetailsChange={this.handleShowProductGroupDetailsChange.bind(
this
)}
onBUChange={this.handleBUChange.bind(this)}
onCountryChange={this.handleCountryChange.bind(this)}
/>
)}
/>
</div>
</div>
</div>
</div>
</HashRouter>;
Can anyone tell me, why the url is updated, but the component not?
UPDATE
I already searched a lot and I found this link on the react training site.
I tried different things, but no one did not solve my problem.
But when I change HashRouter to Router it works fine!!! Why!?!
Can it be an issue / bug of HashRouter?