Arduino for STM32

Hard to tell without the full code added.
Do you declare "MyBoards" properly?

Arduino IDE 2 have/had issue with menu update. On older version of the IDE (prio 2.3.x), the menu is not refresh at startup.
This could explain your issue.

For ref: https://github.com/rogerclarkmelbourne/ ... issues/923

I would recommend to simply declare the new boards entry and add it to the existing variant for the blackPill F411CE. Like it is done for the *PillF103: https://github.com/stm32duino/Arduino_Core_STM32/blob/3d6e84b3d8cd072f8230a4aa8bd114f5e4a70945/variants/STM32F1xx/F103C8T_F103CB(T-U)/variant_PILL_...

Discussion follow here: https://github.com/orgs/stm32duino/discussions/2348

Try to debug using Arduino IDE 2.2.1.
The latest version 2.3.x changes the debug configuration way. I will fix this within next release.

Simply enable the optimize for debugging option and you should be able to debug and see where it stucks.

You should redefine the system core clock config to properly configure the pll vs the HSE value.

Pay attention it seems you set 80MHz and not 8MHz

Is the LED_BUILTIN correct for this new board?

https://github.com/stm32duino/Arduino_C ... adaptation

https://github.com/stm32duino/Arduino_C ... efinitions

So simply create the file with at sketch level :
#define HSE_VALUE 800000000U