Lighting, Lumens, and the Circle of Light

Can someone help me understand why, when I drop my lumens down to a reasonable level, the shadows cast by my lighting just end in a ball of light. If bump the lumens to supernova levels, the ball of light expands. See attached for examples.

The large light in the background is set at 1,000 lumen point and spherical source. It generates nice shadows on distant walls and is pretty ideal. The lights in the foreground are set at 500 lumens point and spherical source. The cast shadows just....stop....a few feet from the light.

If I crank up the foreground lumens to 1,000, the shadows expand but just, jeez, I am searing my eyeballs.

Then, if I go big and set the foreground to 5,000 lumens, the shadows *dont* expand, everything else just gets dimmer due to autoexposure.

To further experiment, if I drop the lumens of the background light, the nice, big ball of cast shadows does not get smaller. The foreground light intensity is set to 150 lumens and the background is set to 300 lumens in this image.

I understand regarding the difference in the size of the pattern. What I cannot figure out is why the shadows being cast stop so abruptly. Attached is an image of the light in a niche. The shadows should be reaching the sidewalls of the niche and elongating along the back wall of the niche. Instead, the cast shadow pattern just stops about 2' from the light source. It shouldn’t do that.

Changing the light source geometry does not have an affect on the cast shadows. I made it 3" in size and 6' in size, with no change.

I am attaching both lights, to help troubleshoot.

Thanks much.