I don’t remember reading on here whether anybody mentioned the actual valve stem and whether it has been changed or not because the rubber will deteriorate over time and as a rule you should change the valve stem every two tire changes if you’re using the stock valve stems. Are use the heavier duty steel ones which will last a lot longer. Even then I usually change those out after the third tire. I had the same issue with my rear tire and it turned out to be the valves stem. At first I thought it was the core, but changing that had no effect. I always carry a spare valve stem cores, But I will be adding the actual valve stem to my little parts box in the saddlebag.