Mob farms won't work

[everton1712]

mob rally spawn and they don't track at all unless I hit them
And nothing fixes it I can stand 2 blocks away and they won't track

 

[Emmmma]

oh dear.

 

[jasonstover9]

I went into Skyblock to see if its a global problem. Its not, I was clobbered by several right in my island that saw me from a distance and started coming towards me.
According to Minecrafts help pages the best I can get is that a glitch especially in mobs is often caused by a poor internet connection. Sometimes to many things going on with the WiFi in your house can lead to oddities in game. The tracking is in the code. Within so many blocks ( I think zombie pig men are 37 or something like that) a code starts that determines what the mob does. If your mobs are not tracking you the code is choppy and not consistent on your client.
If it were me, I would restart my internet and/or reduce items using WiFi in the house.
This is all just my opinion. The issue may be totally different for you.