Why can't Shapefiles created using Spatial Modeler be edited in ERDAS IMAGINE's 2D View?
It appears that many Features-based operators (such as Buffer Zones and Convert to Features) are creating a 3D Coordinate Reference System (CRS) on the output Features (even though the vertex height information may not have been populated). Which in turn means you get a 3D Shapefile if your Features Output is set to the Shapefile format.
3D Shapefiles cannot be edited in the 2D View. This is why the Shapefiles created using Spatial Modeler can not be edited in ERDAS IMAGINE's 2D View.
Detailed explanation and workaround provided as a Spatial Recipehere.