iray light probe kit

beyonder2k9

https://www.daz3d.com/ig-iray-light-probes

Has not been working since 4.20

nemesis10

https://www.daz3d.com/forums/discussion/551301/ghost-lights-what-s-happening-and-what-s-next/p1

https://www.daz3d.com/forums/discussion/548061/iray-ghost-light-fix-dse-for-daz-studio-4-16

https://www.daz3d.com/forums/discussion/575741/problems-lighting-with-emissives-recently

The short answer is that ghost lights were based on a hack that nvidia just patched so their behavior has changed. There are various fixes (see links)