"topChildren" property for facets is getting overwritten

Hi,

We are have implemented faceted search in our site. we are using properties below properties for facet extraction. We have updated "topChildren" property to 2000. But after some time, "topChildren" property is always re-setting back to 100 (which is a default value). As  a result, During facet extraction only 100 facet buckets are getting extracted from result. We have analysed the logs, but couldn't able find anything. Any pointers/guidance to avoid re-setting it to default value?

http://localhost:4502/oak:index/damAssetLucene/facets.tidy.1.json

{

  "jcr:primaryType": "nt:unstructured",

  "topChildren": "2000",

  "secure": "statistical",

  "jcr:content": {

  "jcr:primaryType": "nt:unstructured",

  "multivalued": true

  }

  }

Note: We are using AEM 6.5.1 version

Thanks,

Vineeth