Okay, until the bug is fixed, I've found a solution.

As I wrote before it's about downgrading the platformio version

but in my previous tests you didn't have use the flag -- force reinstall.

To get platformio back ok, do this:

Open Visual Studio Code
Wait for platformio to be loaded
click on the platformio icon on the left 
from the choices that open up choose
Miscellanous -> new terminal

in the terminal window that opens type

pip install "platformio==4.0.3" --force-reinstall 

press enter

Wait for the command to end. 

then check the version change with 
platformer --version

press enter

must show 
PlatformIO, version 4.0.3

I didn't need to restart, but do it for safety.

Now build as usual and you'll see that the project.bin will load
perfectly on the printer