Not monitoring HR during activities

My Steel HR watches (I have three of them) all consistently fail to monitor HR during any of the activities (even gentle ones such as walking). After ending the activity, the watch just reports “Not enough HR data. Your HR was not captured properly during this session.” Have tried all trouble shooting steps and multiple wearing positions using three people… not one success in measuring HR during an activity (no problem in sleep or normal wear). After weeks of communication, Withings has stated that this is a known problem, despite their advertising claims, and has offered me a refund. Has anyone else had problems?