From here
As shown above, the effective sample size per iteration has drastically improved, and the trace plots no longer show any “stickyness”. However, we do still see the rare divergence. These infrequent divergences do not seem concentrate anywhere in parameter space, which is indicative of the divergences being false positives.)
and similarly here :
These infrequent divergences do not seem concentrate anywhere in parameter space, which is indicative of the divergences being false positives. As expected of false positives, we can remove the divergences entirely by decreasing the step size,