Hi Jon,
Thank you for contacting Syncfusion support.
We have checked with the provided information and we are able to reproduce the Appointment over lapping issue in time line view. We have logged issue report on this. We will fix this issue and include this in our upcoming Volume 3 SP1 release which is expected to be available by end of October 2018. We appreciate your patience until then.
Regards,
Deivaselvan