Swimlane (mobile): moving UI elements on touch device (android tablet) does not really work

I was testing the current hzt.vortanz.ai swimlane on a tablet (Samsung Galaxy S3, Chrome browser). The UI looks good on the device and it works well to jump to annotations by tapping on the marker. But when I try to move the markers, it seems as if I can't really drag them around within a bigger time range. It seems as if they can only be moved a few frames back and forth (feeling that the interface is stuck). It's the same with start & end points + the red time needle. After moving the annotation, it mostly kept a pale colour and the UI seems to hang (e.g. time needle does not update anymore).