ide 2.0 cannot find new com port adding after ide started and must be exit & rerun to find new com port
@jefpou Which Arduino board do you have, official or a clone? Trying installing the core for your board, see www.arduino.cc/en/Guide/Cores.
Secondly, you can also install the latest stable IDE version, 1.8.15. Both IDEs can run independently, so you can choose which one to use after testing both. IDE 2.0 is still beta version.