Did you do this?
Vinp inp 0 DC=1.5 AC=0.5
Vinn inn 0 DC=1.5 AC=-0.5
And then for your transient add this line:
Vtran inp inn SIN(0.8 10m 10k)
There's no way it will work with your input DC=0 due to your common mode input range. Your common mode range is:
-Vss+Vdsat3+Vtn-Vtp < Vcmdc < Vdd - Vdsat5 - Vdsat1 - Vtp
So for example, if your Vdsat= 200mV for each transistor, Vtn = 0.7, Vtp = 0.9, then your input range will be:
0+.2+.7-.9 < Vcmdc < 3.3 - .2 -.2 - .9
=
0 < VCMR < 2
Theoretically it will work at 0 V input, but it will be right on the edge of saturation/triode, so this is not a good bias point for this example.