Susan, the link to your earlier post is not working and I am running into a similar issue. Can you post the link again, or copy the information.
thank you
I
I lost the link to this as well.
But go into ArcGIS Administrator -> Advanced -> Manage Portal Connections
Make sure the portal and agol entries are there.
Test the connections.
If that still fails
Goto Control Panel -> Internet Options ->Advanced - Security
Uncheck
Check for publisher's server revocation
Check for server certificate revocation