Proxy doesn't work, while executing jail_code there is no output displayed

Hello,
I would like to execute this python code (containing a print statement and a sleep call for 1 second for each iteration of the range(5)).

The idea was to test and see if PROXY is working as desired. I was excepting to see while executing jail_code.jail_code(...) in the stdout of my terminal progressively displayed the numbers second by second:

1
2
3
4
full-output
- 0
- 1
- 2
- 3
- 4

but didn't happened..
First one should be the output printed by the proxy, and the second one is when I iterate on the result object stdout.

from codejail import jail_code
jail_code.set_limit("REALTIME", 20)
jail_code.set_limit("CPU", 100)
jail_code.set_limit("FSIZE", 10000)
jail_code.set_limit("PROXY", 1)

code = """
import time
for i in range(5):
    print(i)
    time.sleep(1)
"""

res = jail_code.jail_code(
    "python",
    code
)
print("full-output")
for line in res.stdout.decode('utf-8').split('\n'):
    print("-", line)

The issue here is that during this execution of jail_code.jail_code(...) the PROXY didn't seems to print anything in the output is that normal, I'm missing something ?
Thanks in advance.
PS: I have CODEJAIL_TEST_USER/ENV and CODEJAIL_PROXY configured in my ENV.

Start by reproducing the provided Python snippet with the configured CODEJAIL_TEST_USER/ENV and CODEJAIL_PROXY settings, then trace jail_code.jail_code(...) and the proxy's stdout handling. Determine whether progressive output is expected or whether only res.stdout is supported; done means the behavior is clarified and, if it is a bug, covered by a suitable regression test.