There's also activity on PGC on the AMD PC after 13.6s. I went back for a better pic in case it was an issue with the zoom not yet picking up a short signal:

Name: U2 pgm 16F877 Easy Quiz - Compare zoom max.jpg Views: 1398 Size: 198.3 KB

I'm definitely missing pulses on the C2Q PC and have no clue why that would be.

Either something is wrong with the USB ports, which is unlikely 'cause every other device works properly; gaming wheel/yoke/thrust quadrant/joystick, mouse, keyboard, digital camera, logic probe, etc.

Or something is wrong with the U2 programmer at the driver level, 'cause the hardware works properly on the other PC.