It is not possible to use Serial 1 via Arduino on the STM32F407IGT6.

[camerakang]

STM32F407IGT6.zip
I created a variant of STM32F407IGT6. When I wanted to use UART1 (PA9, PA10), I encountered a problem. No matter what I did, no signal appeared.
platformio.ini:
[env:STM32F407IG_Arduino_User] platform = ststm32@^18.0.0 board = STM32F407IG_Arduino_User framework = arduino build_flags = -DUSE_HAL_DRIVER -DHSE_VALUE=25000000U -DSERIAL_UART_INSTANCE=1 -DUTOOLS_USER_CONFIG_H=\"../../../include/utools_config.h\" -DDEBUG_LEVEL=3 -DSERIAL_TX=PA9 -DSERIAL_RX=PA10 -DHAL_UART_MODULE_ENABLED -I include lib_deps = stm32duino/STM32duino FreeRTOS@^10.3.2
init:
Serial.setRx(PA9); Serial.setTx(PA10); Serial.begin(115200);
or
HardwareSerial Serial_topeet(PA9, PA10); Serial_topeet.begin(115200);
I don't know what I did wrong. When I use the HAL library to initialize and call UART1, for example, "HAL_UART_Transmit(&huart1, (uint8_t *)"Initialization of detection system!", 36, 1000);", it works.

[fpistm]

Hard to tell.
Seems you used FreeRTOS. Try without.
Also try with Arduino IDE.

[fpistm]

Test with a disco F407VG (close to F407IG) and it works. As I do not use PIO nor support I could not help.