Development tools for Zephyr on STM32Workbench for Zephyr: VS Code extension to set up, build, flash and debug Zephyr applications on STM32.Devicetree manager: browse, edit and visualize Zephyr devicetree, STM32CubeMX-like for Zephyr.
Could be due to reset issues with the board,. Does the debug probe have a reset connection to the MP? Many boards do not, especially 4 wire SWD boards.
See previous post "stm32f4 with nucleo-f401RE"