Zookeeper Exhibitor: "ERROR Index Build: there are 0 available backups"

[archmangler]

I see an index listed after creating on in UI, and clicking on the index I indeed see a list of entries I can restore.
When I click to create "New Index" I see the following logs are generated, leading me to believe the backups are not being created:

Tue Mar 27 15:46:00 UTC 2018	INFO	Index completed: /var/zookeeper/snapshots/exhibitor-1522165558794
Tue Mar 27 15:45:59 UTC 2018	INFO	Indexing active log 7 of 7
Tue Mar 27 15:45:59 UTC 2018	INFO	Indexing active log 6 of 7
Tue Mar 27 15:45:59 UTC 2018	INFO	Indexing active log 5 of 7
Tue Mar 27 15:45:59 UTC 2018	INFO	Indexing active log 4 of 7
Tue Mar 27 15:45:59 UTC 2018	INFO	Indexing active log 3 of 7
Tue Mar 27 15:45:59 UTC 2018	INFO	Indexing active log 2 of 7
Tue Mar 27 15:45:58 UTC 2018	INFO	Indexing active log 1 of 7
Tue Mar 27 15:45:58 UTC 2018	ERROR	Index Build: there are 0 available backups
Tue Mar 27 15:45:58 UTC 2018	ERROR	Index Build: Getting available backups
Tue Mar 27 15:45:58 UTC 2018	INFO	Starting index build
Tue Mar 27 15:43:30 UTC 2018	INFO	State: serving
Tue Mar 27 15:43:30 UTC 2018	INFO	Exhibitor started

I'm not sure how to explain the "Index Build: there are 0 available backups" message, though. My configuration seems to be correct, as follows:

cleanup-period-ms=300000
check-ms=30000 
client-port=2181
connect-port=2888  
cleanup-max-files=20
backup-period-ms=600000
backup-max-store-ms=18000000
observer-threshold=0
auto-manage-instances=0
backup-extra=/var/zookeeper/backuplogs
log-index-directory=/var/zookeeper/snapshots
zookeeper-log-directory=/var/log/zookeeper
zookeeper-data-directory=/var/lib/zookeeper
zookeeper-install-directory=/usr/local/lol

I start exhibitor like this:

 java -jar /opt/maven/target/exhibitor-1.6.0.jar --port 8888 --defaultconfig /nfsshare/exhibitor/exhibitor.properties --filesystembackup=true --hostname `hostname` --servo=true --configtype=file --fsconfigdir /nfsshare/exhibitor