Platform-ps4
Steps to reproduce-shoot a tank repeatedly and stay behind the tank at all times until the tank stops moving.
Host or client- host
Players in game-singleplayer
Description-I encountered this bug while shooting a FNIX tank with a exp shotgun.After a min I realized that the tank wasn’t trying to kill me I tried this on another tank and it happened again it seems staying behind a tank and shooting it with any shotgun prevented it from attacking.my character was level 31(max level) but it seems to work with any level and second character.
You can destroy the device that causes the aoe attacks, so maybe you did that.
when shooting off the weapons i usually always get them to behave strangely. i usually snipe off the weapons with either pvg or ak so i try to stay at a certain distance. as soon as the weapons are gone and im too far away for him to stomp they often just do what looks like a little shuffle dance 
when getting closer a little bit they sometimes get themselfs together again and try getting closer to stomp.
that tactic works for me aswell, taking of the weapons, and tick-pod,andthen go and humiliation-kill it with whatever i have on me. and like you say its like they do this little one step forward onestep back dance, i think it has something to do with them getting their foot stuck in the ground or something. as for the exp shotgun, i too find it extremely effective against tanks. simply because each shot staggers the tank, and one shot stops them from doing whatever they were doing, shoot one when its charging up its melee, and the melee will get canceled. super effective