Solved
Freertos semaphore not initialised correctly by CubeMX
By setting up a new project in STM32CubeMX 6.10.0, when adding a Semaphore in FREERTOS, the generated code is not correct, and the binary semaphores are initialised in a Taken state ( initial_count=0 of osSemaphoreNew() ) - resulting in the fact that the application will never be able to take the semaphore - see code snippet below.
/**
* @brief FreeRTOS initialization
* None
* @retval None
*/
void MX_FREERTOS_Init(void) {
/* USER CODE BEGIN Init */
/* USER CODE END Init */
/* USER CODE BEGIN RTOS_MUTEX */
/* add mutexes, ... */
/* USER CODE END RTOS_MUTEX */
/* Create the semaphores(s) */
/* creation of i2sHalfCpltReadySem */
i2sHalfCpltReadySemHandle = osSemaphoreNew(1, 0, &i2sHalfCpltReadySem_attributes);
The correct function call should be with initial_count=1 as here below and how it was in older MX versions
foo = osSemaphoreNew(1,1, &bar);
For users having the same issue: quick fix is to add these line after initialisation
/* USER CODE BEGIN RTOS_SEMAPHORES */
osSemaphoreRelease(i2sHalfCpltReadySemHandle);
For ST Employees: please fix Cube MX to properly initialise.