Put the summary of the bug you're having here

I built an endermen farm that operated in previous Snapshots
They don't fall so I have to kill them with my sword (sharpness and sweeping edge)

What I expected to happen was...:

Most mobs should receive a damage

What actually happened was...:

I hit them, but only one damaged

Note: Sometimes the sweeping edge does work

 Steps to Reproduce:

1.summon some mobs into trap (like in the photo)
2. hit them with sweeping Edge sword