CZML delete of static entities

In Cesium 1.13, we’re seeing the issue with the polygon is never deleted visually. Codewise, it’s pretty straight forward:

viewer.dataSources.add(czmlDataSource).then(function(result) {

// hook up a callback to result.loadingEvent

// hook up a callback to result.changedEvent
// hook up a callback to result.errorEvent
// hook up a callback to result.entities.collectionChanged

The callbacks just logs to the console.

The polygon CZML is pretty straight forward as well: a polygon with referenceFrame:FIXED, cartesian:[(~75-150 points)], material:solidColor with rgba for example [255,255,0,51]. Image a polygon representing the daynight line with the night part filled in with an alpha. Updates for the same polygon (i.e. daynight area) are coming up close to every minute, sometimes faster.

Deletes packet looks like

{id:, delete:true}

When the CZML delete comes in, the polygon is still showing with 0 entities in the collection (from the callback logs)… if we force another update of a different polygon area, then the daynight area polygon is then cleared out.

Is the CZML delete package a right approach?