5 yo Border Collie stopped coming when called; stands and stares or runs away

My crazy smart Border Collie has decided to not come when called. He hears me but as soon as I say his name to come (which he used to do happily and immediately), he looks away from me, runs the opposite direction and then turns and stares. If I make any approach to him, he runs further away and does the same thing. It has gotten to be very frustrating and at times, his lack of obedience has caused me alot of issues when I can’t leave him out. I have tried everything I can think of or researched, he is very strong willed and “tricking” him won’t work because he remembers any tactics one might use to get him to come inside. I love his intelligence and his desire to “watch” the house is a job he takes very seriously, but can’t figure out why he stopped coming and how to retrain him to do it if food is not a motivator.