Here's what worked for me: Login to Apple Developer Account > Go to App Store Connect > Sandbox page. Here the page will be blank (expected). Next, click on the 'Integrations' tab right next to it. Turn off WiFi/hotspot (basically any internet connectivity). Now, again click on 'Sandbox' tab. Now you will see the '+' button. Click on it and fill all the information BUT DO NOT SUBMIT YET. Turn on your internet. After you are connected to internet, click on submit. Aaaand you are done. Note: This was suggested by another user in a different thread which I am writing here in detail so that it is easier to follow for others too. Hope this helps!