No TestFlight invite email gets sent for internal users

Question

I set up my application for TestFlight. For external users it is waiting for review. But if I want to invite internal users, I select them and press invite. iTunes Connects says

Answer 1

I tried it all, but none worked. Than I realise I was using a new email created for this sole purpose and hadn't used it in the App Store yet.

So the solution is simple:

1. Log in with your new Apple ID in the App Store.
2. You will be requested to finish your sign-up, filling info about address and title.
3. No credit card information is needed, just leave it as none.
4. After accepting the terms and log in in App Store, deselect the internal tester user in iTC, save it, select it again and then invite.
5. All previous invitations got delivered in no time and all together.

Another bug i'm facing is that the app never finishing install in test flight app, but actually it is installed, just leave the app, and you will find it in the home screen.

Hope it helps someone.