Here's a different tack entirely:

A friend of mine took in an abandoned puppy which had been living rough under the air conditioner at church. It was very afraid of people. She fed it, captured it, and took it home, yet it didn't get tame or friendly at all. Named it Lacey, for Lady-a/c.

She did some reading and learned that she needed to let the dog sleep in her room at night. When a pack of dogs rejects a member, it refuses to let that dog sleep with the pack. So when my friend made Lacey sleep in the kitchen, Lacey thought she was being rejected by her new pack. When she got to sleep in her owner's bedroom, she calmed down and became a good pet.

So, where does Max sleep? If not with you, then maybe he too thinks he is being rejected by his new pack.
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Another friend had a corgi who often ran away, trying to find a herd to herd. I always thought she (the corgi) ought to get a job in a day-care center.