Hello guys, I've been working on this for months and it's driving me crazy now. I ordered the whole package from DJI with T-Motor F55 Pro II + F4 HD STACK.
As you guys can see from pics below, I believe I have figured everything correctly. 1. UART 2 MSP and UART 5 RX are set on, which is a bit different than others, as this is F4 HD STACK. 2. Modes have been set up too. 3. HDL is on, as I have set 'set sbus_baud_fast = ON' already, and it is shown on my goggle too. 4. all voltage information is shown on my goggle too.  

All in all, all the testing works well, except one problem, the remote controller cannot control the motos, which means the motors have no reaction to the remote controller.  But I can see the bars change in BF when I play remote controller, and the motors also react if I test them from 'Motors' in BF.
So, until now, I have excluded all possible mistakes, could you guys give me some help?