Venu HR Accuracy problems

Hi all,

This morning I did a weightlifting workout with my new Garmin Venu (fit securely on my left wrist), and used a Whoop (right wrist) and Wahoo HR strap as my controls. I clicked the "Train" activity option in the Garmin, since the Strength one seemed to want me to do some sort of guided workout. All three devices had good contact during the workout.

While the Wahoo and Whoop were fairly aligned, they could have been better. That said, they both said I burned about 500 calories during the workout. The Garmin on the other hand, never really recorded high HR and said I only burned around 100 calories. Is this because I picked the "Train" activity option? I would think that the activity type would not have that significant of an impact on the HR measured.

Any ideas on why this might have happened? Screenshots below.