Originally Posted by
Often1
It's not fingerprints because you don't have GE. It's also unlikely anything to do with a watchlist because you aren't having secondary issues.
Of APC kiosk users visiting the using again using the US VWP with a valid ESTA, fingerprints are still relevant to being admitted into the country. For US persons and Canadian citizens, fingerprints indeed don't generally matter unless using GE since the non-GE kiosks -- that is the APC kiosks -- don't demand fingerprints of such persons.
It's possible that the OP may be blacklisted in some way, whether or not the blacklisting was a deliberate outcome or a product of system handshake failures of sorts. Some blacklist hits don't involve the hit person being directed consistently/routinely/ever to a secondary.