Cluster split animation is inaccurate

[CostinTanasoiu]

Hi, I've noticed some strange behavior: when zooming in, some clusters will split, but the animation and smaller clusters into which they split are misleading. I have recorded this behavior here: https://www.screencast.com/t/psP4s4bu

When zooming in, the orange cluster with 6 items seems to split into two clusters with 4 items and 1 item respectively. However, what isn't noticeable at first is that one of those 6 items actually gets redistributed into another cluster. If you look at the tooltips in the video, it's the item labeled "32 Grosvenor Gardens, London SW1W0DH".

Basically, from this:

to this:

It would be super useful if the animation showed that item splitting from the big cluster and moving into the other cluster.

I have seen this happen quite often too, with other clusters.