After an axe stuns a shield (via crushing blow), when attacking once more, rather than damaging the shielding player while their shield is down, it instead resets the stun timer again. This prevents axes from damaging players that are using shields while their shields are stunned. Axes should be able to attack players normally if the attacked player's shield is already stunned. This has been a bug since 1.9 released and was never fixed.

NOTE: THIS BUG ALSO EFFECTS THE NEW JAVA EDITION COMBAT SNAPSHOTS