I can find no error in your schematic. I have simulated just one of your opamp stages - and the result is as expected: lowpass response of second order.
Now you should do the following:
1.) Simulate only the first part of the circuit - that is the RC-element together with the first two-opamp stage. For this purpose, disconnect R7 from the opamp output and ground R7 (in order to avoid an error mesage).
This should give you a lowpass of third order.
2.) At the same time check the value of the power supplies. The DC bias values of app. 360kvolts look very strange. Even if something is wrong, I cannot understand why the power supply is at such a high value. Perhaps you should do this test at first.
Good luck and report about the results.