As @jrus says, this problem isn’t apparent in Chrome because it supports ResizeObserver. You can tell Observable explicitly that the content of a cell has resized by dispatching a load event on that cell. For a transition that is continuously resizing the cell, you’d need to dispatch a load event on every tick, like so:
But it might be better to resize the SVG element only once at the beginning or end, instead.
Usually you don’t have to tell Observable that a cell resized because Observable checks the size after the cell is evaluated. However, here you’re reaching into the DOM produced by a different cell (and the mutation is happening inside of an async transition) so Observable doesn’t notice.
Given that the mutation is happening inside of an async transition, it wouldn’t work without the dispatch event even if I would reach into the same cell.