nRF51822 Le secure connection

Hello all.

I am developing a BT4.2 compliant application.
I have a question about LESC (LE Secure Connection). 3-0-and-nrf51822 / 142314 # 142314
I had add the above process.

But, if you connect using "nRF Connect" on a PC, a DHKEY error (BLE_GAP_SEC_STATUS_DHKEY_FAILURE) will occur.
And connecting with "nRF Connect" on ipad pro results in unspecified error in Public key exchange.

However, I can connect with the module I created.

Any idea what might be happening?

【Development environment】