Why does quadric/color disappear?

JT Tyler shared this question 6 months ago
Needs Answer

Hi, GeoGebra help desk asked me to post this because they didn't know the answer. Can someone let me know why the color (and shape) disappears when the 'd' value gets above zero? If you play with that slider bar (d) you'll see that if you move it to zero, and then away from zero, the blue quadric will disappear. Sometimes you'll have to repeat this a couple of times to see (what appears to me to be) this bug.

https://www.geogebra.org/m/j7vjbddk

Thanks!

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