Python API failing when launch with supervisor

Dear all,
I have a Python program to pilot a CNC. I'm used to launch linuxcnc and my python program via supervisord and it was working fine with linuxcnc 2.8.
I'm testing it on a new machine (debian 12/linuxcnc 2.9) and i'm facing the following issue: the python program works perfectly if I launch it manually on the command line, but fails without a clear error message if I launch it via supervisor. Basically, the first call to linuxcnc.stat.poll() fails, as if linuxcnc was not launched (but it is).

Any clue about what could cause the problem?
Thanks in advance for any hints,
Regards,