Hey @claracurrier, could you please share a code snippet?
Did you do sth like the following? If so, the default process group is a per-process state, so you will need to call init_process_group in the beginning of the spawn target function (i.e., target_fn), not after spawn in main function.
def main():
    spawn(target_fn, args=(...))
    init_process_group(....)