new STM32L431 chip first time running failed

Hello,

When programming an ELF file into a new STM32L431 chip(blank FLASH) for the very first time, the program does not start running automatically. It only runs correctly after a full power-off reset.

However, after this initial procedure, new ELF files can be programmed and executed directly without requiring a power-off reset.

What could be causing this issue? I recall that the STM32G0 series had a similar problem.

**Additional details:**
- BOOT0 is connected to ground via a 1M ohm resistor.
- The STLINK V3 MiniE Vtarget is connected to the board’s 3.3V supply.
- OB setting is not touched.

Thanks!