Question about walrus punch

I know walrus punch has interacted strangely with ranged heroes for a long time now.

I was just wondering if anyone knew the mechanics on when the stun works and when it doesn’t.

It seems to work when you are within a certain range of the enemy, but if you’re too far it procs the crit but not the stun, and then your projectile animation sometimes disappears.

Do you have to be within your heroes attack range to proc the stun or is it something else that causes it?