SharedList appears empty in second thread, but full in main thread

sharedlistprobs.nim

import logging
import os
import sharedlist

type
  FunctionLogger = ref object of Logger
  LogFunc = proc(msg:cstring) {.raises: [Exception], gcsafe, tags: [TimeEffect, WriteIOEffect, ReadIOEffect].}

var LOG_FUNCTIONS: SharedList[LogFunc]
LOG_FUNCTIONS.init()

var logger {.threadvar.} : FunctionLogger 

proc init_logging*() =
  ## Set up logging if it isn't already set up
  ## Must be called once per thread if you want logging
  if logger.isNil:
    new(logger)
    addHandler(logger)

method log*(logger: FunctionLogger, level: Level, args: varargs[string, `$`]) {.gcsafe.} =
  echo "log: ", $getCurrentProcessId(), ".", $getThreadId(), " ", $args
  echo "logger.isNil: ", $logger.isNil()
  if level >= logger.levelThreshold:
    echo "in threshold"
    let ln = substituteLog(logger.fmtStr, level, args)
    for fn in LOG_FUNCTIONS:
      echo "LOG_FUNCTION yes"
      fn(ln)
    
proc register_logger*(fn:LogFunc) =
  ## Register a function to receive logging events from Nim.
  ## The function will be called with strings to be logged.
  echo "adding log function to LOG_FUNCTIONS ", $getCurrentProcessId(), ".", $getThreadId()
  LOG_FUNCTIONS.add(fn)