I received this error when installing the interactive grid sample application on apex.oracle.com (workspace SAGE).

And later when attempting to save in one of the pages I received this:
ORA-29861: domain index is marked LOADING/FAILED/UNUSABLE
I wonder if my workspace is low on resources, but I did try truncating some tables before retrying. The monitor workspace report didn't come back with results so I wasn't sure.
Scott