Alexa appinventor: no connection to Amazon

I am working with alexa appinventor (

After creating a new project and adding a skill (Button Add Skill…), I wanted to log in to Amazon (Button Login to Amazon), but I got a blank window:

The url of the opened window:

url:MIT App Inventor - Login to Amazon

gives an error-description when you look at the details of the url.

I have an Amazon Developer Account and used alexa.appinventor already in year 2020.At this time it worked fine!

I hope someone of the appinventor developers can help to solve the problem,

thanks in advance!