Help with inverter simulation
You forgot to connect several of the terminals in the schematic (the ones that have the yellow X marks over them).  The PMOS source and back-gate need to be connected to a supply, and the NMOS source and back-gate need to be connected to ground.

Also, don't bother laying out the circuit until the simulation is working based on the schematic.  You should be able to get the final layout DRC and LVS clean.

Edit: I'm not sure why it's not working with the new schematic.  Did you set the supply voltage? (It's possible that the supply symbol isn't actually doing anything besides setting a net name.)