It looks like you might have placed the Scheduler in an absolutely-positioned element that is displayed as a top layer.
The Scheduler also supports a special mode where it fills the available space:
https://doc.daypilot.org/scheduler/100-pct-height/
So make sure that you aren't using heightSpec: "Parent100Pct" config option.
Note: I'm removing the "lite" tag - the Scheduler component is only available in the Pro version.