I am a Global Admin in our Nintex Automation Cloud environment.  I have a connection to Sharepoint which I have used before.  The permissions for this connection show that I am the owner and everyone is a user for this connection.  I tried to use it in a workflow today and it didnt appear as a choice of connection to use. I had another user also test and she could not use the connection either.  She was not an owner of the connection.  I looked at my previous workflow that used the connection and its broken there too.