Saw this a couple of days ago on Neokyo too (Apple iPad version).
On entering the Alley Sprint one of my robopacers appeared. People in view before the robopacer appeared were normal however, after riding for a 100 metres of so any new people (and a cat) coming into view appeared as grey ghosts (same colour as the robo pacer). I assume this could be the models switching into view and the bug is using the material of the robopacer on these people (and cat). The robo pacer finished before I did and the people beyond the finish line were normal when I got there.