Thanks @DrDiettrich
I'm sorry, please read breadboard, not breakout board...
The full diagram is large on several boards, but the way touch button and I2C expander are powered on the breadboard and the PCB are the same:
- Arduino powered by 12v + mosfet reverse voltage protection + big capacitor for devices requesting peak current (actually not connected)
- I2C expander and touch buttons powered by the arduino 5V output
I also tried to power the arduino with USB only. It makes no difference, works on the breadboard, but not on the PCB.