Why are my accelerated reports not leaving the "Summarization not started" state?

[chustar]

In my search head cluster, one of my accelerated searches does not seem to be able to run its summarization.

It's summary status keeps flipping between:

Summarization not started
and

0% Complete

It also reports that: Last Updated: 22h 59m ago.

How do I diagnose why this report does not run?

Edit:
I was seeing this error in the splunkd.log:

Line 90050: 10-11-2017 10:10:49.817 -0700 ERROR SHCRepJob - failed to delegate job job=SHPDelegateSearchJob peer="TC-SPLUNKSRCH2", guid="<GUID>" saved_search=system;; err=error accessing https://<SEARCHHEAD2>:8089/servicesNS/a-markle/search/shcluster/member/delegatejob/_ACCELERATE_<SEAR..., statusCode=404, description=Not Found

But after a rolling restart of the cluster, it seems to be running again:
Its summary status is now reporting as:

Building summary - 6%

[blacknight659]

This is a tough one.

Can you check the job inspector or perhaps the splunkd.log? ,Hard to say what is happening. Can you post anything from the job inspector or perhaps the splunkd.log?

[chustar]

Thanks, I've updated the question with an error from the splunkd.log.