Hi,

When mapping areas inside outer areas you have to ensure that 100% of the 'inner' area nodes do not share any single node with the 'outer'.  In this case I've mapped the woodland along the river areas around and removed several river areas as inner to the wood on the river banks. See https://www.openstreetmap.org/changeset/160704218 how it was done. It can be done real quick since JOSM and ID Editor have a line trace/follow function to draw lines around areas.

Cheers