The bug

Tamed foxes sometimes stop about 1 block away from the target when attempting to attack instead of actually going to them, resulting in the fox not being able to hit the target unless the target moves toward the fox.

This occurs more frequently with baby foxes.

How to reproduce

1. Summon a zombie

   /summon zombie ~ ~ ~ {Attributes:[{Name:generic.movement_speed,Base:0},{Name:generic.attack_damage,Base:0.1}]}

2. Summon a tamed fox

   /execute summon fox run data modify entity @s Trusted append from entity @p UUID

3. Walk into the zombie on Survival mode
   → The zombie hits you
   → The fox attacks the zombie
   → At some point, the fox will stop in front of the zombie and will remain stationary