Meanwhile, I've tried a few more things.
Uninstalled from the iPad, test on iPhone, nothing.
Log out/in on iPhone, still nothing.
Uninstall/reinstall on iPhone, still nothing.
Reinstall on iPad, start getting notifications on iPad, WITHOUT even opening or logging in on the iPad.
I have this problem. iPhone 3Gs iOS 6.1.6, Chess.com iPhone App v2.12.28
Tried logging out/in, then rebooting the phone, then uninstalling/reinstalling app. Still not getting notifications.
However I am getting notifications on my iPad 3 iOS 7.1