The scheduled search is scheduled properly and runs with no errors per _internal log. However the search artifacts are never retrievable. Through a few months of working with support and several troubleshooting binaries, we have discovered that this is caused by some bug with Splunk failing to properly run scheduled search queries that begin with a pipe.
E.g.:
| inputlookup
| tstats
Currently awaiting response and a fix from Splunk. Not sure if other versions are affected.
Fixed in version 6.2.7 and 6.3.*