The mix looks good, the volumes …
but A.J rejected …
what could it be ?
everything was going so well …
and now, everything goes bad with A.J 
I feel your pain, its not like no one is buying any of your tracks.
In my opinion there are no obvious shortcomings in the track, in general everything is OK. The only thing I paid attention to is the main melody (harmonics). Unfortunately, I don’t know how to explain this correctly in the language of musical theory, but it seemed to me that the movement of the melody was not entirely logical. Maybe it’s in the intervals between notes, maybe it was worth making this melody even easier. It sounds throughout the entire track, even when the “breakdown” starts. Perhaps it would be worth giving a break from it. The sound of the clap seemed to me too “dancing”, not quite suitable for this genre, but perhaps this is already nit-picking) Cheers!
In my opinion, it needs a melodic lead, beginning at about 16 bars in, as well as overall thematic and sonic development. As is, it sounds to me like a background track, not a complete production. Hope this helps. Good luck!
Nothing terribly wrong with your track, but I simply think AJ are starting to reject more of these types of tracks since they come in by the THOUSANDS.
So unless it’s really, really good, it is likely to get rejected. This one isn’t bad, but could easily be replaced by 10,000 other tracks already online.
Let’s look at an analogy using images.
At the beginning of the stock photo boom, sunsets were submitted, and were quite successful. Since it’s one of the easiest and most obvious things a photographer can photograph, they started coming in by the thousands, if not hundreds of thousands.
At some point the agencies stopped accepting them unless they were absolutely spectacular. People still bought sunset pictures, but there is no need for 1 million of them.
Flumen, Good Point, The saturation point is very high, At the same time I’m not sure there is any genre that is wide open opportunity right now as far as AJ is concerned, And everyone is always told look at the top tracks. Maybe you have some other insight to share…
To me it sounds nice and ok for a background track. The one thing I can comment is a bit too much ambience/reverb/delay. Listening to promoted aj tracks, it seems usual to have a lot of it on some instruments, but here it somehow builds up too much and the mix doesn’t sound clear. Most instruments are pushed back in the soundstage. Which might actually be good for a background music, I guess. Hi hats are not clear, but might be compression/encoding issue on soundcloud.
Try eq-ing your reverbs/delays and (especially that you’ve got a piano in there) watch for those low mids ~250Hz.
That’s the first impression at least. Hope that helps. I’m not an authority on mixing at all 
(ps: don’t listen to my tracks, they’re old 
)