SPI + sd_app_evt_wait and nested interrupts?!

sdk15, SES, SD132

Hi
I am using an SPI slave with nrf52 (master)

I launch in the main() and I also initialize the SPI slave on main.
I also configured an app timer and when it fires I read the SPI slave using nrf_drv_spi_transfer (burst read) for 9 bytes.
and then I wait for the spi transfer like this:

while (!spi_xfer_done)
{

    uint32_t err_code = sd_app_evt_wait();
    printf("SPI status=> %d count %d\r\n", err_code,count);
}

The problem is that the loop never ends. It seems that it is an interrupt nesting issue.
Can anyone tell me if it could be an interrupt nesting problem and if so how can I solve the problem?

Thanks

Alex