My project builds when set to Release, but fails when set to Debug. Here are the last few lines of the transcript output:
1> "C:/Program Files/SEGGER/SEGGER Embedded Studio for ARM 5.34/bin/mkld" -memory-map-segments "FLASH RX 0x0 0x100000;RAM RWX 0x20000000 0x40000" -section-placement-file flash_placement.xml -check-segment-overflow -symbols __STACKSIZE__=8192;__STACKSIZE_PROCESS__=0;__HEAPSIZE__=98304 -section-placement-macros FLASH_PH_START=0x0;FLASH_PH_SIZE=0x100000;RAM_PH_START=0x20000000;RAM_PH_SIZE=0x40000;FLASH_START=0x27000;FLASH_SIZE=0xd9000;RAM_START=0x20001d28;RAM_SIZE=0x3e2d8 C:/nRF52840/nRF5_SDK_17.0.2_d674dde/projects/ble_central/ble_scanner/pca10056/s140/ses/Output/Debug/Obj/ble_scanner/ble_scanner.ld
1> Linking ble_scanner.elf
1> "C:/Program Files/SEGGER/SEGGER Embedded Studio for ARM 5.34/gcc/arm-none-eabi/bin/ld" -X --omagic -eReset_Handler --defsym=__do_debug_operation=__do_debug_operation_mempoll -EL --defsym=__vfprintf=__vfprintf_float_long --defsym=__vfscanf=__vfscanf_long --gc-sections -TC:/nRF52840/nRF5_SDK_17.0.2_d674dde/projects/ble_central/ble_scanner/pca10056/s140/ses/Output/Debug/Obj/ble_scanner/ble_scanner.ld -Map Output/Debug/Exe/ble_scanner.map -u_vectors -o Output/Debug/Exe/ble_scanner.elf --emit-relocs --start-group @C:/nRF52840/nRF5_SDK_17.0.2_d674dde/projects/ble_central/ble_scanner/pca10056/s140/ses/Output/Debug/Obj/ble_scanner/ble_scanner.ind --end-group
1> C:/Program Files/SEGGER/SEGGER Embedded Studio for ARM 5.34/gcc/arm-none-eabi/bin/ld: Output/Debug/Obj/ble_scanner/thumb_crt0.o: in function `memory_set':
1> C:/Program Files/SEGGER/SEGGER Embedded Studio for ARM 5.34/source/thumb_crt0.s:287: undefined reference to `main'
Build failed