PTSF_GENFEED Failed for Crawling Post Upgrade to OpenSearch

After upgrading to OpenSearch, when scheduling search indexes using the new search instance based on OpenSearch (where the indexes were deployed and crawled prior in the old search instance on ElasticSearch but now un-deployed in the old search instance after the OpenSearch upgrade), the App Engine PTSF_GENFEED keeps on failing with the following:

PSAESRV started service request at 07.32.59 2024-05-03


Starting program PTSF_GENFEED (35,36)

Resuming the previously  failed schedule from: Post processing ,recrawl mode :Full index,language: Base Language and prompt: 1900-01-01-00.00.00.000000. (262,92)

Error in fetching the document count : not_found (262,2168)

Process 283287 ABENDED at Step PTSF_GENFEED.ES_STAT.Step01 (PeopleCode) -- RC = 20 (108,524)

Process %s ABENDED at Step %s.%s.%s (Action %s) -- RC = %s

PSAESRV completed service request at 07.33.42 2024-05-03