Resolved! Error with timeouts constants in stm32f7xx_hal_sd.c in SD_SendSDStatus and SD_FindSCR cause indefinite hangs.
Both these functions contain the code:"if((HAL_GetTick() - tickstart) >= SDMMC_DATATIMEOUT)"However SDMMC_DATATIMEOUT is defined as 0xFFFFFFFF so the timeout is very long (49 days with a 1ms tick) and therefore never occurs.That upshot is that if the...