In onUpdate method I have changed the return conditions to the defined in documentation:
onUpdate: Callback function triggered when an item is about to be updated, when the user double taps an item in the Timeline. See section Editing Items for more information. Only applicable when both options selectable and editable.updateTime or editable.updateGroup are set true.
Attemp to solve https://github.com/yotamberk/timeline-plus/issues/169
In onUpdate method I have changed the return conditions to the defined in documentation: