As it says in the title, is this expected behaviour?
What happens is that the dataset before the area on area overlayer has some features (in the image below, the large green parts are the same feature, there is a point where they touch). The lower part of the green feature is lost when the transformer is run. This shouldn't happen!
I have an example dataset and workspace, here: https://www.dropbox.com/s/n50h39yftp7nhtx/fme_bug.zip.
There are a number of other cases where this happens in my dataset. Any thoughts?