This issue is fixed.
Mobs stop while a warden is roaring. Wardens roar when they detect another mob.
But while a warden is roaring, All mobs stop.
Steps of reproduce
Summon a wardenSummon some other mobsWait a few minutes until the warden detects someone
Expected results
Mobs move normally.
Observed results
Mobs move abnormally or stop.
I could not reproduce, what device are you using exactly and what OS version?