Unfortunately, I have to agree. I wanted to see him kick on here after impressing last season but it just doesn't look like the opportunities will fall into place like, as you said, it did with Mainoo.
If he were to go back on loan, my preference would be Sunderland again because, one, I think he's pretty much guaranteed game time when back to full fitness, and two, the football they play and players they have really give Amad the platform to showcase his abilities. Though, with the recent sacking of Mowbry and appointment of Beale, it could be a different story, but I like what I saw in his first two games against Coventry (despite being beaten 3-0 they played their usual entertaining football) and Hull.
Not to mention his partnership with Patrick Roberts. Their link up play was incredibly entertaining last year, so seeing them two together again would definitely a bonus. I think he'd work well with Jobe Bellingham, too, from what I've seen.