How Fix Spotlight with "Error: datastore publishing not implemented"

Spotlight Mavens,

Since last week's update to macOS v10.13.4 (on a mid-2010 Mac), Spotlight is unable to provide valid responses to simple queries.

Here is a portion (the full response is included at the bottom of this post) of the response to the Terminal command mdutil -p -s -a -v:

/:

Indexing enabled.

Error: datastore publishing not implemented.

/Volumes/HDD:

Indexing enabled.

Scan base time: 2018-05-13 04:47:00 +0000 (476276 seconds ago), reasoning: '(null)'

Error: datastore publishing not implemented.

On two occassions prior to macOS v10.13.4, Spotlight issues on the same Mac were repaired by this series of Terminal commands:

sudo mdutil -i off /

sudo rm -rf /.Spotlight*

sudo mdutil -i on /

sudo mdutil -E /

This time...no joy. Since yesterday (Thur, 17 May 2018), the above sequence of commands have been executed on the affected Mac several times. The result? Spotlight works for a few hours, then degrades and is unable to provide valid responses to simple queries.

After trolling around in this forum, StackOverflow, and the web in general(*), I'm unable to find actionable suggestions to remedy this issue...and hope the fine folks on this fabulous forum an help.

Any ideas? Suggestions?

Many, many thanks.

Plane Wryter

(*)Including attempting these suggestions--which failed due to macOS' SIP (System Integrity Protection):

sudo launchctl unload -w /System/Library/LaunchDaemons/com.apple.metadata.mds.plist

sudo launchctl load -w /System/Library/LaunchDaemons/com.apple.metadata.mds.plist

----------------------------------------------

Full Response to mdutil -p -s -a -v

/:

Indexing enabled.

Error: datastore publishing not implemented.

/Volumes/Data:

No index.

Error: datastore publishing not implemented.

/Volumes/HDD:

Indexing enabled.

Scan base time: 2018-05-13 04:47:00 +0000 (476276 seconds ago), reasoning: '(null)'

Error: datastore publishing not implemented.

/Volumes/Time Machine Backups:

Indexing and searching disabled.

Error: datastore publishing not implemented.

/Volumes/Time Machine Backups/Backups.backupdb:

Indexing enabled.

Error: datastore publishing not implemented.

/Volumes/com.apple.TimeMachine.localsnapshots/Backups.backupdb/iMac/2018-05-18-0 31039/HDD:

Index is read-only.

Error: datastore publishing not implemented.

/Volumes/com.apple.TimeMachine.localsnapshots/Backups.backupdb/iMac/2018-05-18-0 41101/HDD:

Index is read-only.

Error: datastore publishing not implemented.

/Volumes/com.apple.TimeMachine.localsnapshots/Backups.backupdb/iMac/2018-05-18-0 71118/HDD:

Index is read-only.

Error: datastore publishing not implemented.