OnCollisionEnter Straightfoward(very) question

void OnCollisionEnter(Collision col)
{
if (col.gameObject.name == “Ball”)
{
Debug.Log(“hit”);
}
}

Ball hits the block... why no print line?

First, put another log line before your IF statement. If that line prints in console, your problem is in

if(col.gameObject.name == "Ball").

If that is not the case, check this documentation about unity colliders. Especially focus on the collision tables on bottom of the page.