For those A9 Pro users who bought their units at Widget City or Kimstore and who are experiencing problems regarding SIM 2 not sending or receiving messages, just check you Message Center Number. It always resets the message center number to the sim card that is placed in SIM 1.
If you have globe in sim 1 and sun in sim 2, everytime you restart your phone, the message center number for both sims will be that of globe. Just edit the message center of sim 2 to the network you are using for sim 2. I don’t know why this happens but it fixed this problem.