No Response to SMP Pairing Request

I am using the DA14583 with an external host (TI DSP). The prox_reporter_ext_spi example has been built and loaded in the 14583 flash.

Communication between the TI DSP and the DA14583 seem to be working correctly as I am getting the expected BLE messages at startup (GAPM_DEVICE_READY_IND, PROXR_CREATE_DB_CFM, etc).

Using a sniffer, the 14583 is advertising correctly. When I try to pair it with my phone, however, the pairing fails. In looking at the packets, the phone sends an SMP pairing request and expects an empty PDU packet back from the 14583. This packet is never sent. I'm fairly certain that the 14583 is getting the pairing request as I'm getting a GAPM_CONNECTION_REQ_IND message at the TI host.

Is there something in the initial configuration of the 14583 that would cause it to not respond to the SMP pairing request?

For reference, I have tested the 14583 with the DA14580DEVKIT using the prox_reporter_ext project with the PC as the external host. Pairing with this example works correctly and there is little difference in the connection sequence when using the sniffer. With this project the 14583 sends the empty PDU packet as expected and then follows up with the SMP Pairing Response.