Hey CosmosD,
I have actually looked at the project today. What you can try is to go into your TestBoidsPawn.cpp class and add this line of code under your RootComponent = PlaneMesh; line.
PlaneMesh->SetCollisionResponseToAllChannels(ECollisionResponse::ECR_Block);
This will need to be altered to only set the response to the object channel of your boid since you created a custom channel for it. Go ahead and give this a try and see if it works for you.