Embed tab not displayed with autostart

I like my linuxcnc machine to be ready automatically. The session opens automatically and launches a little script that waits a few seconds, launches my linuxcnc config and offers to shut down the system when I leave the linuxcnc interface.

This script works very well, even on another machine at work. But I'm having a little problem with a custom embedded tab in place of the cooling buttons I use to control my dust collector.

When I run my config by hand, it usually displays correctly, but with autostart, my button is missing. Even without using my little script or extending the delay.

It's a LinuxCNC ISO that's a bit old (maybe two years) but updated, so maybe that's the problem, because at work, on a machine where I've used a more recent ISO, I don't have any problems.

My current LinuxCNC version: 2.9.3
GMOCCAPY: 3.4.8

I've attached my script, my ini file and two screenshots

It's quite strange. But it doesn't matter.
I'm curious to know what could be the problem.
Thanks

maybe writing the terminal output to a file could provide some clues

Thank you, I had indeed forgotten to do this.

Even stranger, when I run the script by hand, the log file fills up, but this isn't really interesting because in this situation everything works correctly. But when it's run automatically, the log file remains empty.

Maybe add a debug output to the autostart command:

... >> /home/axel/autostart_log.txt

I had also tried, same problem

Maybe it is sending the output to stderr not stdout. This should direct both to the file: