I have discovered an issue with markers hopping while using relative_to_ground and 3D tiles. Removing disableDepthTestDistance: Number.POSITIVE_INFINITY sometimes makes the marker less jumpy. On a related note using positive_infinity sometimes results in marker flicker while when it is not set, the flickering does not seem to occur, I have found a couple of other threads where people had this issue and I am confident it is related to disableDepthTestDistance. I should note that the hopping is understandable with the LOD changes but this continue to occur even after tiles are loaded.
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Sand Castle: Cesium Sandcastle