Magic Buckets should display whichever screen (Magic Intervals or Magic Endurance) is appropriate to match Today’s advice (HIT or LIT).
If a workout is scheduled today on the Planner or selected on the Training page, that is the low/high/peak values MB will sync with along with a Focus Power target (example, Mixed Breakaway Specialist).
If you have an XFAI forecast plan make sure to select Choose Training to assign the workout/activity you want to ride, not [+] Add.
EDIT: This doesn’t mean you have to Choose a workout on the Planner or select a workout on the Training page for MB to work. If you don’t have a workout assigned on the day MB will sync to the general advice for that day. For example, Polar Rouleur (6-minute power), XSS: 115 (106 | 7.3 | 1.9) or Pure Endurance (LTP), XSS: 82 (82 | 0 | 0)