So, people keep saying that the Sheer Heart Attack entity doesn't attack npc's. Hopefully, people read this before commenting.

This problem usually happens when the map doesn't have a navigation mesh. To solve the problem either choose another map to use SHA on, ask the map maker to add a navigation mesh to the map, or generate a navigation mesh through the console.

To generate a navigation mesh through the console, open the developer console and type this command into the console: nav_generate. This will freeze or slow down your game for a moment. After it's done generating a navigation mesh, from now on, Nextbots will work on that map.

I made a poopy video about this. Forgive the quality of the video, I tried my best.
https://www.youtube.com/watch?v=WI9D4bpA0Co

Hopefully this helped!