Esc does not reply

Hi, We have a small project where we use an stm32V407 panel(our) connected to ESC 4.20 through UART baud rate 57600. Stop bits parameter is 2 We use only a few functions from the esc. These are the bldc_interface_get_values and the bldc_interface_set_rpm. The bldc_interface_set_rpm works fine and the motor does what it should. But the bldc_interface_get_values does not work according to our expectation. Our panel polls the ESC in about 100ms frequency the ESC panel and there are really seldom replies for this message. (Reply arrives around every 4 seconds). With oscilloscope and debugger the sent out message seems OK. And when the reply arrives it contains realistic data. Have you seen any issue like this before? Lajos