Client 98 is empty and because there is nothing to index the index process never marks this client as "indexed". The message can be safely ignored in such case because nothing is actually rebuilt.
Update to a fix version listed below or a newer version if available.
Component(s): Automation Engine
CA Automic Workload Automation v12.1.3 - Planned release 2018-09-24
CA Automic Workload Automation v12.2.1 - Planned release 2018-10-23