I have a problem with the Aggregator transformer producing invalid geometry. A shapefile with 4 polygons is initially passing through a Geometry Validator (all tests) and are all passing. An Aggregator transformer is then used to merge them and an identical Geometry Validator after this is finding un-repairable self-intersections in the geometry and therefore failing my workspace. Has anybody had this issue before?

 

 

The Aggregator has default values set apart from grouping the 4 polygons by an attribute.