Cannot Load libpepflashplayer.so in electron app on Linux

I’ve made a sample to execute flash in an electron app … i’ve followed the tutorial https://electronjs.org/docs/tutorial/using-pepper-flash-plugin

My sample works fine on Mac, Windows but it fails on Linux (Ubuntu and CentOS 7) …

I’ve a message in my Electron Window saying “could not load the plugin” without any other information … no error logs, no warnings. So i dont know the reason …
The path to the libpepflashplayer.so is ok … when i set it with appendSwitch. I’have activated the plugin: true in WebPreferences of the browser Window

Is there any way to have more logs or events to understand what happens ? did somebody has the same problem ? is it a known bug ?

Thnsk