I created a library for uart communications:
https://github.com/gianmarcov/arduino_vesc/tree/develop

With the WROOM ESP32 it's working and i have no problem, with the nano 33 BLE Sense i tried the same sketch changed the Serial2 to Serial1 and nothing happens, i also swapped rx and tx to the other board without results.

I have remote debugged the other controller and i see only 2 bytes incoming the other not.

So i soldered the wires to SWD pins and i flashed my own code without Andruino Core etc. directly using the Nordic nRF52 SDK and now it's working without problems.

So something is going wrong in the Arduino Core or MBed, that all bytes are not transferred via tx.

if you have questions or i should test some code changes don't hesitate to contact me.

Thread that i created in the Forum:
https://forum.arduino.cc/index.php?topic=639277.0