Hi Phil4E,
Based on your description, you cannot open documents from SharePoint in browser.
This issue was posted to the Service Health Dashboard (SHD) as incident SP92058 starting at January 27, 2017 4:25 PM (UTC). The user experience of this incident is: Users may be unable to open and save Word, Excel, and PowerPoint documents in the browser. Tenant
administrators can view current information and updates on SHD at the link here
https://portal.office.com/admin/default.aspx#@/ServiceStatus/ServiceStatusHistory.aspx.
If you are experiencing a similar issue and do not see an SHD post, please let us know by sharing your tenant information via Private Message (PM) as this may indicate either a scoping issue or an independent problem. https://answers.microsoft.com/en-us/privatemessages/list
For affected customers to easily identify the information here, this thread will be closed. You may subscribe to this thread or refer to SHD for updated information. I will also post back here once the issue is resolved on SHD.
Thanks,
Yoga