Has happened to me several times - normally it is hidden behind a trees from yet unexpanded plots. Sometimes I try to place something on the plot ( like habitat, which covers the entire plot) - to see where exactly is the obstacle . If I'm lucky then sometimes I've been able to even click on the obstacle then and remove it - just watch when you see the " pay coins in the bottom corner" - sometimes you are able to find it - even if you don't see the obstacle itself.
If this doesn't work - then yeah - you need to expand, until you can see.