@BoM_M5 I had the same problem today. In Arduino IDE v.2.3.3, BOARDS MANAGER, searched for esp32. Found "esp32" from Espressif Systems. It appeared that I had version "3.1.0 RC" installed. On Espressif's site on Github I saw that the latest stable version is: "3.0.5", so I downgraded to 3.0.5. Then I saw that the M5NanoC6 was available via: Tools -> Board -> esp32 -> M5NanoC6. After having selected this board, I saw also that: Tools -> CDC on Boot was "Enabled". I saw that there was here no more option "Disabled".
From this moment all Serial.print and Serial.println command worked as expected.
B
