Oracle search regularly needs reingesting index

Summary:

We keep having a recurring issue where users cannot find employee records in Oracle Redwood Search (or can only find in Advanced Search in RUI pages), but as soon as we run the initial ingest process for the fa-hcm-person index we can find them fine.

We should not need to keep running the initial ingest job, but it seems we are running it quite regularly to fix this issue. Note: We have the incremental index job running throughout the day as per Oracle Search configuration guidance. We have double checked our Oracle Search configuration and it is as per Oracle requirements.