With the calendar, it works a bit differently than it did when you had set workouts on set days and you could assign one ride in place of another.
If you look on the calendar, you’ll see for today’s date that you completed the 8-min FTP test and (if you already added the plan to your calendar), you will see a skipped Ramp Test workout.
What I would do is just delete the Ramp Test from the calendar and replace with the 8-min FTP test, and you’re good to go.
If you haven’t done this already, you should go to TrainerRoad career page, select your plan and at the top right “Add to Calendar”, select your starting date… and all of the workouts will populate onto the calendar.
When I change workouts, I simply remove the scheduled one, click on the day and then there are options to search for a new workout to add. Alternatively, you can just search “workouts” from the web browser, and ‘add to calendar’ any workout on any day you wish.
Does that help?