If you're exporting a lofted object you probably need to convert it to a mesh. It sounds like you can't see your model because the loft data gets lost when importing into jpct.
Don't know about blender but in 3dsmax I would collapse the mesh then reset the xform and centre the object at world zero.
Don't know about blender but in 3dsmax I would collapse the mesh then reset the xform and centre the object at world zero.