[The example](https://visjs.github.io/vis-timeline/examples/timeline/markers/customTimeMarkersEditable.html). It seems to be caused by an id collision <img width="561" alt="スクリーンショット 2019-10-05 21 57 41" src="https://user-images.githubusercontent.com/14275842/66255174-6f141b00-e7bb-11e9-9443-f555c6884ccc.png">