Has anyone experienced error in Serial data transmission from an Atom Lite BUT ONLY when you simultaneously send Serial data to the Atom?

I have tested different boards (Teensy, Arduino NG, Arduino Nano), and this is the only one that has this issue.

I wrote about it here : https://github.com/m5stack/M5Atom/issues/86

If the computer does not send data to Atom Lite, the Atom send the sequence 0 to 255 without a problem.

But when I simultaneously send data from the computer to the Atom Lite, there is errors on the sending of the sequence from the Atom Lite.

What do you think is going on?