I am logged in to Stack Exchange/Arduino with my StkEx OpenID. I followed a link to a Stack Overlow question, where I am also a member (I have some rep and badges there), but SO doesn't recognize me as logged in.
I returned to my Arduino profile -> Network Profile. My network profile says I have some rep and some badges in SO. I followed that link to my SO profile which does exist and agrees with the Network Profile (rep and badges). Yet following any SO link on my SO profile page displays SO as though to a stranger. Those would be the SO logo in the upper LH corner of my profile page, and clicking on one of my own SO questions listed on my SO profile page.
Why is SO asking me to log in again, while I am logged in?
Update: Requested screenshots:
Logged in at Arduino:
, yet unrecognzied at SO: