Lumped ports in HFSS?
Check your model carefully and make sure you have things connected where you intended. (and not connected as well) Really zoom in and examine the model.
You might also want to look at the HFSS/boundary display (solver view) to see if the model boundaries and materials are correct.
Another idea is to build a very simple model and gradually add more detail as the simple model(s) "work". Build from simple to complex.
If you really get frustrated call one of the Ansoft application engineers. They are very helpful and usually don't laugh where I can hear them.
Make sure you provide DC and RF return path. I imagine your bondwire goes from the ground plane to die plane. These two plane must be connected. You can create a 2-D perfect-E sheet connecting the two planes, or you can use a PEC brick connecting the two planes.
wlcsp