Hi @mattsidare. The "Arduino Mbed OS Portenta Boards" platform of the Portenta X8 is not configured to support use of the board with the Arduino IDE 2.x integrated debugger.
At the current time, the only official Arduino boards platform which is configured for use with the Arduino IDE 2.x integrated debugger is the "Arduino SAMD Boards (32-bits ARM Cortex-M0+)" of the MKR boards, Zero, and Nano 33 IoT. Of those, the Zero is especially convenient to use because there is an on-board debugger.
The Arduino IDE 2.x debugger is designed to support any microcontroller with an ARM Cortex-M, and can likely be used even with microcontrollers of other architectures so long as they have GDB support. So it is mainly a matter of the boards platform author adding a couple of necessary configuration properties. I am not aware of any 3rd party boards platforms that have added that configuration at this time, but I'm sure we will be seeing more adoption as time goes on.
Now, all of what I said above is specifically about the Arduino IDE 2.x integrated debugger (since you highlighted the fact you are using this IDE). If you are using another tool for debugging then of course the question of whether the Arduino IDE 2.x integrated debugger supports the Portenta X8 is irrelevant.
Thanks for the information. Do you know if there is a combination of IDE and debugger that I can use when developing for the 32 bit cortex m4 core on the Portenta x8?