If you have a start/end time that does not include the current time then the current time marker will give the schedule odd behavior.
So for example if the start/end time is 8:00AM - 10:00AM but the current time is 3:00PM.
Sometimes there is a red arrow that locks to the top of the scheduler. I have also seen the the issue create a large whitespace below my calendar with a red arrow/line underneath. Setting the [currentTimeMarker]="false" solves the issue. I would expect that the marker would just not show anywhere if the time range does not support it.