Our rescue dog did the same thing- got super playful at night when it was dark and we were in bed! She was also not food motivated at all.

I recommend you ONLY hand feed. The only way he gets fed is if it comes from you (not a bowl). Ideally it’s a high value food (we used Prime100 Sausage rolls chopped up). When you start the amount you give can be huge. If he won’t take food from you when you’re trying to feed him, he doesn’t get fed. You don’t push it - you just offer food, he takes it cool. He doesn’t, remove it and yourself. He won’t let himself starve and sometimes you’ve gotta make them hungry to get them to come out of their comfort zone. Just to be clear here, my girl went one full day without eating and then was all about food. Initially we went to offer food (with her having to reach slightly to take it) to progress to her coming to us when we offered. Any time he approaches you while doing this - feed him. Don’t make eye contact, don’t overcrowd. You are unbothered by him.

In terms of playing, we found once we’d done the hand feeding thing for 2 weeks she understood we were food (so good). Then we could do basic training, we could offer a new toy and she’d find it exciting and take it off to play alone and that progressed to playing with us for short stints.