Hey there @PatMag68! As @Arkiras had finished saying before I did, Lumen doesn’t gather from tiny objects as raytracing cannot feasibly hit every square inch of anything without incredible overhead. You can however try and get some better reactions by following what Arkiras said, as well as increasing the final gather and lumen scene quality. That said it will get exponentially more expensive to do so, so be very wary!
A thread with my answer on how to change some of those settings: