according to the delve of the druid pet stun (other pets may use same stun) it should be stunning at 500 range, currently, it only stuns when in melee range.
Issue Timeline
20 Aug 2018 Prometheus created this issue
21 Aug 2018 Arctic triaged this issue
21 Aug 2018 Arctic changed the status of this issue from new to open
21 Aug 2018 Arctic assigned this issue from Nobody to Arctic
22 Aug 2018 Arctic assigned this issue from Arctic to Nobody
26 Sep 2018 gruenesschaf assigned this issue from Nobody to gruenesschaf
26 Sep 2018 gruenesschaf changed the status of this issue from in_progress to resolved