Done Spikes not killing the mobs

Recently i made a mobfarm using cursed earth and Diamond Spikes to kill the mobs.
There is a small problem. The spikes dont actually kill the mobs.

They take one hit and then they stop.

Spoiler: gif

The spikes are enchanted with Reaper V, Looting III and Sharpness V

 

I think this has happened before, but test it in single player and see if it's buggy there too.

 

Downloaded the map with the command and it worked first time.
When i was testing on single player, the server restarted. After the restart it seems to be working.