Overlapping search only works with standard match semantics, which report matches as they're found.This is discussed a bit in the context of Hyperscan in rebar. In particular, overlapping iteration uses state from the previous search, so it knows where to pick back up in both the haystack and the automaton. Inaho-corasick, there are no wildcards to delay a match being reported or any other way to forceaho-corasick to search the entire remaining haystack on each successive iteration.

The docs could probably use some beefing up with time complexity guarantees, but there in general shouldn't be any surprises here.