What sort of 'actions' do those studies pertain to, though? Simple stimulus-response exercises? If so, I don't think anyone is denying the existence of reflex

What sort of 'actions' do those studies pertain to, though? Simple stimulus-response exercises? If so, I don't think anyone is denying the existence of reflexive or conditioned responses to external stimuli, but that in itself does not disprove that we retain the capacity to insert conscious reasoning between stimulus and response. It seems to be a common pattern when encountering novel situations to analyze them consciously, make deliberate choices prior to taking action, but then to recall those prior decisions in future situations that involve equivalent inputs, repeating the same actions over time, to the point that we effectively "store" our past decisions as conditioned responses that the subconscious can apply directly. Things become "second nature" over time, and develop into habituated actions, but that doesn't mean that there was no conscious thought involved in the experiences that formed them in the first place.