Bode plot does not correspond to output

[ehuang3190]

Hello all,

I'm trying to build a second order low pass Butterworth filter as such:

As expected, the output is attenuated above 40 Hz:

First pic is 20 Hz, second is 60 Hz.

However, the bode plot does not make any sense with regards to these outputs.

What gives?

Any help would be appreciated.