Windows 8 PC added to trusted list but still thinks it's untrusted
Solution 1:
Here are some links that may give you some steps to try. I'm not sure, from reading your original post whether or not you received a verification code via SMS or email. If you haven't done that step, that is the first point of order. I just dug around in the Win 8 forums at MS and pulled these links out. If none of this works, please let us know... I'm sure someone will be able to help with just a bit more information...
Windows 8 'Trust this PC' issue
What is a trusted PC?