Attempted a dynamic follow range modifier system a while ago that didn't work at all. The method was storing their follow range before reducing it to around 4.5 blocks (The area of blindness), and returning it once the effect wore off.

May return to the idea now that I MasterShroob released their dynamic max health modifier. I could look into that to see if anything can be done for mobs and their follow range (Has something to do with storing it in bits)