Microsoft Edge message "session expired".

HHi!  I read and comment on Edge home page off and on all day.  About 10 days ago, I tried to post something and got the msg that the session had expired, followed by "log in to comment".  But I AM logged in and have been for quite a while.  My avatar shows, my history is there, the people I follow are marked, etc. 

I can't figure out what the problem is and it's driving me nuts.  Any ideas would be very much appreciated!