King + two knights vs King + bishop

When I played today a (not regular) game, I got into a situation where I had two knights and my opponent had bishop (move 31). I had always thought this would be automatically declared as draw, but it wasn't. It was declared later, when I took bishop. I don't think there is forceable mate… Same as when there is two knights against lonely king.

There is no general foceable mate, but its perfectly possible that you can get a mate if the position is just right. So you wouldnt want the system to declare this draw by insufficient material.

Yes, but then also 2 knights vs only king shouldn't be draw too…
I would agree if both were immediate draw, or none. I don't get why one should be and the other shouldn't.