Peter Serano
Ansys Employee

There could be a few issues going on depending on how you setup the ports / lumpedRLC boundaries... However, ANSYS Electronics Desktop has it's own built-in circuit simulator and I would recommend using it instead of ADS as it offers many more features as well as a dynamic link to HFSS.

Insert a new 'circuit' design into your AEDT project - then you can drag and drop your HFSS model with lumped port into the circuit schematic to create a dynamically linked HFSS-Circuit model. Terminate the ports in the schematic with your lumped elements and define the system ports, then assign a sinusoidal power excitation to the system ports, then setup & solve a 'linear network analysis'. After it's solved you can right click on the HFSS block in your circuit model and select 'push excitations' which will allow you to visualize any field quantity in HFSS under the conditions defined in the circuit model.

After importing the HFSS model into Circuit - you may also find it useful to enable differential ports to help visualize and ensure the connections are correct. To do this, right click on the HFSS block in the circuit schematic, and select 'Edit Symbol... Pin Locations'. Then in the drop down menu, select 'Add individual reference pin per port'.