Make sure index defnition is updated with orderby for both the properties. More details refer https://docs.adobe.com/ddc/en/gems/oak-lucene-indexes.htmlslide 14 has sample index defnition for order by.Two @ is not valid (@contactinfo/@LASTNAME_STRIP)   just use contactinfo/@LASTNAME_STRIPInstall the...

Find sha checksum of the asset & then in s3 bucket check for the same.Ex:- Asset sample.jpg might have SHA1 checksum as 1607c40f262bc85061703568954d325416c08716  then in s3 bucket check the file stored at/16/07/c4/1607c40f262bc85061703568954d325416c08716

Yes use curl.

Error indicates an permission issue as well as multiple threads trying to commit & descriptions says some times & some images.  I would suspect onDispatcher or webserver level config settings of 412 Status code.Making double requests. Might be facing issue for already activates images with external ...

yes.

Use  http://www.aemstuff.com/tools/coi.html and see if any mismatch.  Otherwise engage with official support.

AFAIK there is no change.  Are you by any chance changing the protocal between http & https?

workflow engine does not support running multiple workflow on same payload.

in cron job you need to call 2 curl command. One to set delay & next is to take a backup.curl -u admin:admin -X POST http://localhost:4502/system/console/jmx/com.adobe.granite:type=Repository/a/BackupDelay?value=0

By default there is delay of 10. If you want to change change the attribute BackupDelay on the same mbean DomainName = com.adobe.granite type= Repository