Defender for Endpoint AMA: The next evolution of automatic attack disruption

What causes inconsistency with smart screen? We're finding that sometimes smart screen works and blocks certain downloads, phishing sites, etc. immediately, and then within moments suddenly smart screen either doesn't work at all for those same situations, or takes much longer than expected to kick in. We can consistently reproduce smart screen's inconsistency with Microsoft's own demos at aka.ms/mde-demos.