180-degree phase shifter shows -90 degree in the graph measurement

Hello,

I am testing a simple high-pass/low-pass phase shifter using lumped elements in AWRDE/Microwave Office. 

The 90-degree shifter looks about right, but the 180-degree shifter shows -90 degrees instead of +/- 180 degrees of shift at 146MHz.

(The L and C values are calculated using the equations here, they are right based on the spreadsheet at 146MHz: https://www.microwaves101.com/encyclopedias/high-pass-low-pass-phase-shifters )

Here is a screenshot of my schematics and graph.  What can I do to read the correct shift for the 180-degree shifter?

Thank you for your help!

-Eric