Apple is aware of this problem, and we are working with them to expedite a fix. This bug affects many Bluetooth devices, not just ANKR. This bug is not present in iOS 8 or iOS 9.
Specifically in iOS 10.0.x, this bug can disable ANKR tracking entirely, requiring you to restart your iPhone. If this does not correct the issue, you may wish to perform a hard reset.
Note: Users on iOS 10.0.x have reported that the problem can return over time, requiring a repeat of this process. We encourage all users to upgrade to the latest version of iOS 10.iOS 10.1 and 10.2 have improved the situation, but Apple still has work to do. We and other, similar device manufacturers continue to lobby Apple to provide a full resolution.
If you experience this issue, please click "Contact Support" in the menu to submit a ticket so that we can notify you when Apple releases a fix.