As discussed with @AlexKlimaj, when UAVCAN_BITRATE = 115200, the flight controller will hard fault when trying to run uavcan and get stuck in a bootloop. The fault log will say something like: “Type:Hard Fault in file:armv7-m/arm_hardfault.c at line: 173 running task: wq:uavcan”.
This seems to be an issue with 115200 specifically, because setting UAVCAN_BITRATE to another number like 500000 works perfectly fine.
I was able to recreate this bug on both the ARKV6X flight controller and the Cubepilot Cube Orange+ flight controller.