updates.oracle.com not authenticating?

My EM13 is complaining that the REFRESH_FROM_MY_ORACLE_SUPPORT_JOB job has not been successful for 72 hours (why it doesn't show up in the failed jobs count is another issue). Sure enough, I am unable to authenticate on https://updates.oracle.com from Firefox or Chrome, either from the OMS's OL7 server or from my desktop. I get:

You could not be logged in

Use your My Oracle Support username and password to login to https://support.oracle.com to access this site. First time users need to register for My Oracle Support

Clearing cookies and logging into MOS (as it suggests) has no effect. The refresh job worked on 2018/05/28, but not on 2018/05/27 or since, so I suspect it's not me.

Anyone else having issues with this?

TIA,
Rich

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