No 3d fix after the setup is done

hi, i have compiled copter 4.3.0 firmware whose HWdef is attached.
whenever i start fresh i am able to get 3d fix but after i am done with the minimum setup for the
flight i am not able to get a lock
4.3.0.param (20.1 KB)

hw definition file for processing by chibios_pins.py

for Diatone MambaH743 mk4 hardware.

MCU class and specific type

MCU STM32H7xx STM32H743xx

board ID for firmware load

APJ_BOARD_ID 1073

crystal frequency, setup to use external oscillator

OSCILLATOR_HZ 8000000

MCU_CLOCKRATE_MHZ 480

FLASH_SIZE_KB 2048

ChibiOS system timer

STM32_ST_USE_TIMER 12
define CH_CFG_ST_RESOLUTION 16

leave 1 sectors free

FLASH_RESERVE_START_KB 384

use last 2 pages for flash storage

H743 has 16 pages of 128k each

STORAGE_FLASH_PAGE 1
define HAL_STORAGE_SIZE 32768

one I2C bus

I2C_ORDER I2C2 I2C1

order of UARTs (and USB)

SERIAL_ORDER OTG1 USART1 USART2 USART3 UART4 UART5 USART6 UART7 UART8

buzzer

PE3 BUZZER OUTPUT LOW PULLDOWN GPIO(80)
define HAL_BUZZER_PIN 80
define HAL_BUZZER_ON 1
define HAL_BUZZER_OFF 0
define HAL_PWM_ALT_ALARM

PA10 IO-debug-console

PA11 OTG_FS_DM OTG1
PA12 OTG_FS_DP OTG1

PA13 JTMS-SWDIO SWD
PA14 JTCK-SWCLK SWD

SPI1 for BMI270 / MPU6000

PC15 MPU6000_CS CS
PA5 SPI1_SCK SPI1
PA6 SPI1_MISO SPI1
PD7 SPI1_MOSI SPI1

I2C1 for baro

PB6 I2C1_SCL I2C1
PB7 I2C1_SDA I2C1

I2C2 for baro

PB10 I2C2_SCL I2C2
PB11 I2C2_SDA I2C2

PC1 BATT_VOLTAGE_SENS ADC1 SCALE(1)
PC3 BATT_CURRENT_SENS ADC1 SCALE(1)

define default battery setup

define HAL_BATT_MONITOR_DEFAULT 4
define HAL_BATT_VOLT_PIN 11
define HAL_BATT_CURR_PIN 13
define HAL_BATT_VOLT_SCALE 11.1
define HAL_BATT_CURR_SCALE 64

PC2 RSSI_ADC ADC1
define BOARD_RSSI_ANA_PIN 12

PE5 LED0 OUTPUT LOW GPIO(90) # blue
PE4 LED1 OUTPUT LOW GPIO(91) # orange
define HAL_GPIO_A_LED_PIN 91
define HAL_GPIO_B_LED_PIN 90
define HAL_GPIO_LED_OFF 1

USART1 (RX / SBUS)

PA9 USART1_TX USART1
PA10 USART1_RX USART1

USART2

PD5 USART2_TX USART2 NODMA
PD6 USART2_RX USART2 NODMA

USART3 (VTX)

PD8 USART3_TX USART3 NODMA
PD9 USART3_RX USART3 NODMA

UART4 (GPS)

PD1 UART4_TX UART4
PD0 UART4_RX UART4

UART5 (SPORT)

PC12 UART5_TX UART5 NODMA
PD2 UART5_RX UART5 NODMA

USART6 (ESC Telemetry)

PC6 USART6_TX USART6 NODMA
PC7 USART6_RX USART6 NODMA

UART7 (GPS)

PE8 UART7_TX UART7
PE7 UART7_RX UART7

PE1 UART8_TX UART8 NODMA
PE0 UART8_RX UART8 NODMA

define HAL_SERIAL1_PROTOCOL SerialProtocol_RCIN
define HAL_SERIAL1_BAUD 115
define HAL_SERIAL6_PROTOCOL SerialProtocol_ESCTelemetry
define HAL_SERIAL6_BAUD 115

Motors

PB0 TIM8_CH2N TIM8 PWM(1) GPIO(50)
PB1 TIM8_CH3N TIM8 PWM(2) GPIO(51)
PA0 TIM5_CH1 TIM5 PWM(3) GPIO(52)
PA1 TIM5_CH2 TIM5 PWM(4) GPIO(53)

Motor order implies Betaflight/X for standard ESCs

define HAL_FRAME_TYPE_DEFAULT 12

LED strip

PA8 TIM1_CH1 TIM1 PWM(9) GPIO(58)

DMA_NOSHARE SPI3* SPI1*

spi devices

SPIDEV bmi270 SPI1 DEVID2 MPU6000_CS MODE3 1MHZ 10MHZ # Clock is 100Mhz so highest clock <= 10Mhz is 100Mhz/16

no built-in compass, but probe the i2c bus for all possible

external compass types

define ALLOW_ARM_NO_COMPASS
define HAL_PROBE_EXTERNAL_I2C_COMPASSES
define HAL_I2C_INTERNAL_MASK 0
define HAL_COMPASS_AUTO_ROT_DEFAULT 2
define HAL_DEFAULT_INS_FAST_SAMPLE 3

Two MPU6000s or one BMI270

IMU BMI270 SPI:bmi270 ROTATION_PITCH_180

one BARO

BARO DPS310 I2C:0:0x76

setup for OSD

define OSD_ENABLED 1
define HAL_OSD_TYPE_DEFAULT 1
ROMFS_WILDCARD libraries/AP_OSD/fonts/font*.bin

define STM32_PWM_USE_ADVANCED TRUE

For this kind of problem, it is not that useful to analyze the hwdef… some more details are needed about the GPS you are using, maybe a log disarmed and a picture of the pre-arm errors poping up in your GCS will be more useful for us to help you.