Wither Skeletons Swinging Swords [Not Attacking Tho], Stuck In Water (Only At Daytime And Clear Weather)

The wither skeletons don't attack when in water, even though there immune to sunlight and swing sword up and down. Btw video i made a about it is here. https://youtu.be/4yWF4toZap4. And the size of the video was too big so i uploaded it on yt