Try changing the user page of the web browser your using. Like change your user page from 'xx' to guest or by adding another user in Google Chrome. If the problem exist in Microsoft edge, do the same by adding a new profile, add a new user, open a page. Then go to mendix, run your app and finally view it. It should work. It worked for me. Make sure that before you click view app, you are in the page that you created as a new user.