HAL_SPI_Receive never returns by timeout

Hello everybody! I'm trying to implement some examples using the hal spi library in the B-L072Z-LRWAN1 (LoraWAN Discovery Board). This board has a STM32LO on it, and I'm trying to implement spi communication with an Arduino.

The ST LoraWAN discovery board is working as slave and Arduino as Master. 

Everything seems to work fine until I turn off the Arduino Board. When I do that, my program never returns from the following call:

status = HAL_SPI_Receive(&SpiHandle2, (uint8_t *)aRxBuffer, 2, 500);

Can't anybody point me in the right direction to discover what I'm doing wrong?

Thanks!