strange results distribution

[sgt101]

Hey - I'm trying Faiss on an entity resolution task. The issue is that I am getting a ranking(5) of 80% or so - with the target distributed evenly between the top 5 results (more or less) and when I go for ranking(1) I get a result of 69%. This makes no sense to me, please can anyone provide an intuition that I can use to understand more about what's happening?

Thanks !