Hi Praneeth, 

Thank you for reaching out. I'm also very confused myself why this happened.

I restarted the program, created a new file, and imported again. But it still didn't work. I'm using Ansys Electronics Desktop 2021 R2. I did the following steps: 

  1. Create a new project
  2. Select Desktop > HFSS 
  3. Modeler > Import > Select stl. files 

Currenly, these objects are viewed as below after the fresh import.

To answer your questions: 

  1. There was no error messgase after the new import. 
  2. The objects are imported as stl. files - they are 3D surface meshes exported from Simpleware (a 3D model generation program). These files worked previously, and showed up like the first image (i just changed the color of the outer object into brown). I'm not sure why all objects appaered to be transparent mesh now. 

Ha Nguyen