[please ensure your code is formatted as code, you can do that using the “preformatted” button in the text editor, or by adding “```” (without the quotes) above and below the code snippet).
Is what you pasted in the entire code, or just a subset of it? Is your DMA using interrupts - if so be aware interrupts will get disabled between any calls to FreeRTOS API functions and the scheduler being started. Where are the transmit buffers allocated - be aware the stack allocated to main no longer exists once the scheduler is started.