While WorldTrackingProvider.removeAnchor() completes without error, the WorldAnchor might be back the next time the App is run. This can easily be replicated by the ObjectPlacement sample. Just add 10 objects, Remove All, then run App again. The first run the anchors might be gone, but run the App a couple more times and the anchors will come back.
This becomes a big problem when paired with the issue that anchors are not always found when the App enter Immersive mode. When an anchor is not found our App will add an anchor. That usually works fine for that run. The next run, however, the other anchors will show up. Anchors accumulate and it becomes difficult to track.
