I looked at the pics before reading and the first thing I noticed was the Saint Bernard-like mask in the bottom right. But after seeing a hound-like build and a hound-like coat I was wondering if the facial markings were coincidental. But then again, he does carry his ears a bit like a St Bernard or Great Pyrenees, and his head is similarly broad across the top.
Are there livestock guardian dogs in your area? Many of those breeds and their mixes can have mask-like markings. For example, I Googled "Great Pyrenees Beagle mix" and some of the results looked quite a bit like your pup.
Also how big is he? That could be a big clue.
We got him aged two years as a rescue (he is now thirteen) and his behaviour back then was erratic and nervous as he was never socialised. To deal with this, we were advised to have treats at the ready to reward good behaviour..i.e. if he did not over react to certain situations. He was undernourished when we got him and so was always preoccupied with food. Fast forward to today...he will chance his arm (paw) to get a treat. For example, he was nervous of people when we got him. He has got over that, but often when out for a walk if someone stops to talk or say hello, he will often (after they've gone) look up at me begging for a treat as if to say....."I did not react to that person... now where is my treat?"
