1040 Edge = 17.26
Fenix 6 Pro = 25.10
True Up enabled.
I sync both devices before ride. I record the ride with 1040 and save to garmin.connect. I see the calorie increase in garmin.connect and new recovery time in 1040.
As soon as I sync Fenix 6 (I did not record anything with it) I see that active calorie value in garmin.connect is minimal again, like If 1040 shows I rode 1800kcal, after Fenix 6 sync I have new random number of active calories, like 400kcal. I´ve seen also new recovery time reset after Fenix 6 sync.
Sometimes, if I leave the Fenix 6 home when I go to ride, True Up works = calories and recovery time in garmin.connect stays on edge1040 values after Fenix 6 sync, but usually not working even with this method.
I have been using Edge 1040 and Fenix 6 combo for almost a year now and I have never found True Up reliable between these devices.