This is not surprising, as energy typically has a gradual and indirect impact on the price of goods and services through changes in the cost of inputs. For example, the cost of offering goods will over time benefit from lower transportation costs.
Similarly, the cost of producing food will benefit from lower fertiliser costs, and the cost of providing hospitality services will benefit from lower heating costs. Core inflation cannot turn on a dime, and the speed at which lower energy prices will pass through to core inflation is uncertain.