A limitation of instinct approaches to motivation is that they fail to explain

See the explanation below.

Explanation:

According to Instinct theory of motivation genetic or biological programming is the cause of motivation and the root of all motivation comes from the motivation to survive and as we behave with this kind of motivation then our action are considered as instincts.

Limitation of instinct approaches to motivation are that:

Many found that instincts are not universal. Humans can show different level of motivation due to instinct. Instinct do not explain all behaviors. Instinct can not be scientifically tested.