It looks like you have changed the a and b input pins to 1, but the evaluate button (calculator) is disabled.
It's also strange that focus is on the reset button as if it had been clicked, but the input values are 1.
I fixed the problem. I had turned the page too early. I didn't build my NOT gate first. Still not sure why my Evaluate button is never active.
I am having the exact same problem. I try restarting the hardware simulator and restarting my computer entirely. As you can see in the screen grab that the original poster showed, when I look at the "Parts Pins" the builtin NAND is giving an output of 1 when a = 1 and b =1.