Haste II and Efficiency V mining speed

With a Haste II beacon active, try mining regular stone with a diamond pickaxe enchanted with Efficiency V.

Expected Behavior: The stone blocks will mine instantly similar to mining netherack with a fast pick
Actual Behavior: The stone blocks will mine slower than expected, with a similar speed to mining with the same pick without Haste II. Spam clicking seems to mine the stone at a faster rate then simply holding down the mine button, which seems odd to me.

A test world folder has been attached

Is this intended behavior or a bug with Haste II not scaling properly with an Efficiency V diamond pick?