Based on the documentation, the default value for file is None. However, if you explicitly provide that as tqdm_notebook(iterable, file=None), you get the "red block". This is a quick little fix for that.

Illustration of problem:

The changes here get rid of that red block.

• I have visited the source website, and in particular
  read the known issues
• I have searched through the issue tracker for duplicates
• I have mentioned version numbers, operating system and
  environment, where applicable:

  import tqdm, sys
  print(tqdm.__version__, sys.version, sys.platform)

4.33.0 3.7.3 | packaged by conda-forge | (default, Jul  1 2019, 14:38:56)
[Clang 4.0.1 (tags/RELEASE_401/final)] darwin

• If applicable, I have mentioned the relevant/related issue(s)

(Didn't see any relevant issues; the fix was so easy that I just made a PR instead of an issue.)