Listen to some tracks in this music category. Learn the ones that interest You the most. No need to try to copy them, but they should pay attention. A large number of sales is not an indicator of good music, but an excellent ability to trade and advertise your products.
You mixed the track well, but You should also pay attention to the orchestral libraries and how You use them. Sometimes it is sounds “midi”. This may also be the cause of rejection.
I also have a few hard rejections. Some of Elite authors have hard rejections! Cheer up! I know you did a HUGE job. But if You don’t stop, You will understand what mistakes You made at the beginning.