Well... I can open it initially. The problem occurs when I save my MXD and reopen the file.
I get the red exclamation point of death and have to add the layer again. See image.
Ignore the ArcGIS Portal reference in the layer group. This stuff is in my Arc Online account.
I am signed in to Arc Online and can see and add the layer again no problem.
It would be nice if I didn't have to do that every time.
Your input greatly appreciated!