If you look at the extraction rules - think from the point - What is the difference between - a routed metal4 drawing [which might take any amount of turns ]- versus an inductor? - how the spiraling metal forms an inductor.
You will discover - it is a dummy layer - inside which, metal4 shapes are not treated as conductor, rather part of device recognition shape.
Now, what does that mean? - it means you should be extremely careful - to not to drop a tiniest piece of unwanted metal shape inside some dead-zone [I didn't say dummy layer, because at times this drawn-dummy is internally sized-up or sized-down]
And, how does it recognize turns - maybe by counting edges, or, number of bends, angled-intersection of edges - and some numerical calculations inside the dummy/dead-zone/device-zone.
While connecting an Ind device - if you inadvertently introduce metal pieces - inside the zone - your device might not form well - or might lead to parameter-mismatch.