As @elpapi mentions the issue typically indicates EBC is in contention with another app connected by BLE. Make sure no other app is running that pairs to your trainer.
I suggest riding all fitness test workouts entirely in Slope mode using gears/cadence to meet or exceed targets and durations.
See: XERT Fitness Test Question - #3 by ridgerider2
Note: To make your activity URL accessible to others go to the activity details, click Share in upper right and select Public.