Application Debug with Bootloader

I can’t debug my application in Mbed Studio. It appears to be down to the fact that I have a bootloader enabled. When I launch a debug session the console spits this out:

0001308:INFO:gdbserver:RTX5 loaded successfully
Attached to debugger on port 50000
0002728:WARNING:builder:Chip erase used when flash address 0x8010000 is not the same as flash start 0xa0000

So looks like the bootloader is erased with the flash erase operation, and only the application.elf, excluding the bootloader is loaded to it’s offset address where it never runs. I’ve tested this out by removing the bootloader options from the mbed.json in my application and running a successful debug session.

I’ve had a look at the linker file for the project, my mbed options and a few other places but can’t see where it’s getting the flash start address of 0xa0000 from.

Can anyone point me in the direction of where this decision might be getting made? One of the Python scripts in the mbed-OS tools directory? PyOCD default profile for this board? Targets? Mbed Studio source?

I just need a way to prevent the flash erase and I reckon it’ll work.

Almost forgot:

Developing on the uBlox C030-R412M LTE board
MCU = STM32F437VG

Cheers.