CD74HC4049: Not Producing Inverting Output in Simulation

Tool/software:

I'm simulating the CD4049UB Hex Inverting Buffer in a schematic in PADS using the IBIS file on the site with the goal of verifying basic functionality. I'm applying a 0V–5V square wave (pulse source) to Pin 3 (A input) and monitoring Pin 2 (G output). I have VDD (Pin 1) tied to +5V and VSS (Pin 8) grounded. However, I don’t see any inversion at the output. the output remains fixed or mimics the input, which shouldn't happen.

Here’s what I’ve tried:

• Confirmed the pulse waveform is correct and toggles between 0V and 5V

• Verified power and ground connections

• Ensured unused inputs are tied to GND

• Used standard timing values for rise/fall time (e.g., 10ns–20ns)

• Tried different simulation tools

• Verified I'm using the CD4049UB IBIS File, not the CD4050B

Attached is my schematic for reference and my input and output waveforms.

What could be preventing the inverter from working as expected in simulation?
Do I need to configure anything special for the inputs or output to simulate correctly?

Thanks in advance for the help!