My 6 month old lab mix cries for 2+ hours after I leave - tried everything and nothing works

I got Biscuit when he was 8 weeks old and hes been amazing except for one thing - the second i walk out the door he absolutely loses it. Like full panic mode crying, scratching the door, the works. My neighbor texted me last week saying she could hear him for almost two hours straight.

I've tried: leaving the TV on, stuffed Kongs, a shirt that smells like me, the puzzle feeders, everything on every reddit thread i could find. Nothing is making a dent. I work from home most days so maybe I accidentally made it worse by being around so much?

Is this just a phase that puppies grow out of, or do I need to get a professional involved? Starting to feel really guilty every time I have to leave.