When life changes the plan
An athlete whose Tuesday session disappears can move that session to another day from their own app, rather than skipping it or waiting until they next speak to you. The workout appears on its new date carrying a Rescheduled marker, in their calendar and in yours, so the plan reads as bent rather than quietly broken.
Most of the time that is the right outcome and there is nothing for you to do. The value is in seeing it at all: a session that moved is a session that nearly did not happen, and a pattern of them tells you something the completion rate alone does not.
Putting one back
Sometimes the move undoes what the week was built around, a long ride landing the day before a key run, say. Click the Rescheduled marker on the workout and choose Restore original date, and it returns to where you planned it.