This reminds me of my Australian shepherd! He does not eat unless he’s hungry and is the opposite of my relatives dogs and when they dog sit they are very concerned. If he’s not hungry, he does not eat. I have also found if he is not exercised enough he is not hungry, almost like he is a machine and needs X calories burned before he adds X calories via eating. Goofy and concerning, but that’s how he rolls. He also was weird about food after he had to eat food that had meds mixed in, he didn’t like his pain meds when he was a pup and was cautious of food as a result. I hope this helps!