You can only inject one mode at a time in the port object. But you can swap the modes and get the full s-parameter to export. You will have to use the “User select” option and select the modes you want and then sweep the modes one by one to get the full s-parameter.
You can also use the s-parameter sweep to automate this process; please refer to the following page for the details on s-parameter sweep:
I hope this could help. I’d love to discuss more if you have further problems on this.