PATHTRACER - Overlapping rectlight limit?

I have a scene with close to 200 very small rectlights in a relatively small area, meaning they overlap a lot – and I can’t seem to add any more. Outside of the concentrated area, they can be added, and it creates a jagged seam between where the new rectlight is visible and where it cuts out as its light approaches the concentrated rectlight area…

I had thought pathtracer was supposed to support nearly unlimited light sources. Is this not the case, at least with rectlights? Thank you for any insights…