Bad light builds when adding dynamic light

I get inconsistent light builds.
This scene has 6 correctly overlapping stationary spotlights.
Building goes fine. If I add a movable light, the build is wrong, with a lot of light, even with all intensities to zero.
Removing the dynamic light removes the problem.

The first image is the normal build, the second with one movable light added, intensity set to 0.

Hello,

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Thanks