Hi Virre,
The "generate raster" option has been removed, and now a raster layer is generated automatically if, and only if, it is required. The cases where it is required are when exporting a project in raster mode, or when exporting a user map where transparency has been used in polygons. Otherwise, the behaviour that you describe I would consider as correct. If, however, you expected a raster layer then this is an error. Could you please describe the map export that you are making?
Matt