Error when calling a external library

[bguil]

Thanks for you efforts with this library!

With Ocaml 4.14.0 and containers 3.9 installed;
in python 3.9.4, I observed the strange behavior below: the first call to ocaml.CCInt.zero fails and the second one is ok.

~ > python3
Python 3.9.4 (default, Apr  6 2021, 11:23:37) 
[Clang 11.0.3 (clang-1103.0.32.62)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import ocaml
>>> ocaml.require ("containers")
>>> ocaml.CCInt.zero
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ImportError: Py.Err(10, "Unbound value ocaml_of_python10")
>>> ocaml.CCInt.zero
0

What is the problem?