New hotfixes changes the Thundering Seasonal affix to have a shorter stun, allows players to run back again and allows all 5 players to be targeted and benefit from the buff without getting stunned.
Thundering Affix Changes
Here is a summary of the latest datamined changes to the Thundering affix.
Players will only get stunned if there is a possible clear target within 100 yards.
The stun duration has been reduced to 4 seconds (was 8).