SPI RX->DMA stops running when debugger is allowed to resume

I'm trying to run SPI2 (Master Receive Only) such that it continuously DMAs data from the slave.

The problem is, it only works when I step over the HAL_SPI_Receive_DMA line... at which point I see SCLK, and it will run forever, until I "resume" the debugger, then SCLK will stop immediately. Similarly, if I just run after reset, (without stepping) there is no SCLK activity.. and if I pause, SCLK remains INactive.

 HAL_SPI_Receive_DMA(&hspi2, (uint8_t*)(&data_rcv), 1);
 while ( 1 ) 
 {
 }

I've tried setting the number of elements to > 1, but it doesn't seem to matter.. the only way I get SCLK activity is if the processor is never allowed to "RUN" after starting the DMA.

I don't have any interrupts and the only initialization is for the SPI2/DMA.. yet something is either causing an SPI/DMA error, or something is stopping the DMA, but I don't have any other code!

Any suggestions what to look at to see what's causing the halt?

 hspi2.Instance = SPI2;
 hspi2.Init.Mode = SPI_MODE_MASTER;
 hspi2.Init.Direction = SPI_DIRECTION_2LINES_RXONLY;
 hspi2.Init.DataSize = SPI_DATASIZE_13BIT;
 hspi2.Init.CLKPolarity = SPI_POLARITY_HIGH;
 hspi2.Init.CLKPhase = SPI_PHASE_1EDGE;
 hspi2.Init.NSS = SPI_NSS_SOFT;
 hspi2.Init.BaudRatePrescaler = SPI_BAUDRATEPRESCALER_32;
 hspi2.Init.FirstBit = SPI_FIRSTBIT_MSB;
 hspi2.Init.TIMode = SPI_TIMODE_DISABLE;
 hspi2.Init.CRCCalculation = SPI_CRCCALCULATION_DISABLE;
 hspi2.Init.CRCPolynomial = 0x0;
 hspi2.Init.NSSPMode = SPI_NSS_PULSE_ENABLE;
 hspi2.Init.NSSPolarity = SPI_NSS_POLARITY_LOW;
 hspi2.Init.FifoThreshold = SPI_FIFO_THRESHOLD_01DATA;
 hspi2.Init.TxCRCInitializationPattern = SPI_CRC_INITIALIZATION_ALL_ZERO_PATTERN;
 hspi2.Init.RxCRCInitializationPattern = SPI_CRC_INITIALIZATION_ALL_ZERO_PATTERN;
 hspi2.Init.MasterSSIdleness = SPI_MASTER_SS_IDLENESS_00CYCLE;
 hspi2.Init.MasterInterDataIdleness = SPI_MASTER_INTERDATA_IDLENESS_15CYCLE;
 hspi2.Init.MasterReceiverAutoSusp = SPI_MASTER_RX_AUTOSUSP_DISABLE;
 hspi2.Init.MasterKeepIOState = SPI_MASTER_KEEP_IO_STATE_DISABLE;
 hspi2.Init.IOSwap = SPI_IO_SWAP_DISABLE;
 HAL_SPI_Init(&hspi2):
 
 hdma_spi2_rx.Instance = DMA1_Stream7;
 hdma_spi2_rx.Init.Request = DMA_REQUEST_SPI2_RX;
 hdma_spi2_rx.Init.Direction = DMA_PERIPH_TO_MEMORY;
 hdma_spi2_rx.Init.PeriphInc = DMA_PINC_DISABLE;
 hdma_spi2_rx.Init.MemInc = DMA_MINC_ENABLE;
 hdma_spi2_rx.Init.PeriphDataAlignment = DMA_PDATAALIGN_HALFWORD;
 hdma_spi2_rx.Init.MemDataAlignment = DMA_MDATAALIGN_HALFWORD;
 hdma_spi2_rx.Init.Mode = DMA_CIRCULAR;
 hdma_spi2_rx.Init.Priority = DMA_PRIORITY_LOW;
 hdma_spi2_rx.Init.FIFOMode = DMA_FIFOMODE_DISABLE;
 HAL_DMA_Init(&hdma_spi2_rx);