PowerApps: Unable to create account due to authentication error

[Deleted]

I am trying to create an app following the New > Create an App and I am getting an authentication error:

Unable to obtain access token for resource 'https://service.powerapps.com/'. Error from ADAL.js: login_required (AADSTS50058: A silent sign-in request was sent but no user is signed in.

Trace ID: 4ba43953-beae-466a-b0f0-3f06fcfc0d00

Correlation ID: 0ab73ff3-e642-4429-9a4c-6b4ad8259051

Timestamp: 2018-09-19 04:50:59Z).

I click on the Authenticate and the loop keeps going on... Any ideas?

[#2]

Mmm...I assume your user have a valid PowerApps license, right?

[#3]

Of course, and I am logged in all apps

[#4]

Thanks!  The problem was fixed after a clear all the cache.

It looks like this happened after setting a shared mailbox on the Outlook Web App... weird...