Expecting to see a visit that isn't there? It's almost always a filter or a view setting, not missing data.
What to check
The date and view. Make sure you're looking at the right day, week, or month. Switch between Month, Week, and Day to widen your view.
Team filters. On the Team Day and Team Week views, a filter may be hiding some people. Clear it to see everyone.
Visit status. Canceled visits come off the calendar. If a visit was canceled, that's why it's gone — the job itself still exists.
Whose visits. A tech sees their own assigned visits; make sure the visit is assigned to the right person.
Note: Visits display in your company's time zone. If times look off, check your time zone under company profile.
Related: Use the Calendar.