We encountered issue on some android devices with versions 6.xx and even 7.xx.
- user installs app;
- proceeds with authentication and it’s successful;
- the device shows phone PIN code screen and keeps asking to enter PIN so user can’t go further;
The workaround is to remove all security locks on phone (PIN, fingerprint etc.) and create new ones.
In this case for some time it works without this strange device PIN loop.
Still trying to figure out how to resolve it on app side.