I'm getting close to launching my first Android app and everything has been going well but about 50% of test users can not login to google play game services. I've combed the forums and followed all of the advice and made sure I have all of the information and google drive/save features on. I've had these players clear their cache and that hasn't worked. I use 2 test devices and they work perfectly. And like I said, half of the players have no problem, but there is no reason the other half shouldn't work as well. Players have checked with other games and they work fine, and their internet is working fine. Also of note, I have version 1.01d I think it is, so I believe I have the latest version of the extension.
Any help would be hugely appreciated. It is the last major issue and leader boards and achievements are a huge part of my game.
Thanks in advance!