Turns out my problem was with having my ArcGIS pro license checked out for off-line use. I deselected this option in ArcGIS Pro and I was able to successfully complete the Update User Type when signing into ArcGIS Online.
See if this is works for you too
I just followed the step to unchecked the off-line used. Sadly, it was not solving my problem.
Finally, I raised an email to Esri support and get a response. After they did investigation, they said that my ArcGIS Online account has BUGS and will inform ASAP if the BUGS have been fixed. I am still waiting for the information right now.