Confirm that this is reproducible with the latest SF. I used the 18 June 2022 "Redfish" incarnation
by Windfishballad (should make no difference since the problem originally showed up with vanilla
SF on TCEC), 96 GB hash, 28 threads. Still replaying the Season 22 VVLTC game 6. Up to Black's
move 15, everything looks normal, with typical time-to-depth -- which of course also means that
said depth is steadily increasing. But already at that move 15 for Black, this doesn't help Fish
very much, since it doesn't see that its favored move 15. ... Qd8 is refuted by 16. Nfd2! Up to this
point though, it still looks like normal behavior (search blindness, overpruning) of the sort that
unfortunately happens from time to time.
But once 15. ... Qd8 is played, SF instantaneously sees 16. Nfd2, and sees that it is pretty much
winning. In 8s, it got to d=27 ... and then got stuck there. No further output was given until I
stopped the engine after 2 hours, even though CPU and memory usage all looked normal. At this
point, this seems to be outright broken behavior, which has persisted for ~6 weeks now.
Is this even still the right place to report something of this nature? Or do all the active devs only
follow Discord these days? I'd have thought that an actual SF search bug would elicit some
response. Or perhaps someone is experimenting with this?