Thanks for your update @jimmbimm
Seems we are not the only ones as there is an open issue on this in Github: [enocean] USB 300 cannot be set up in OH4 · Issue #15181 · openhab/openhab-addons · GitHub
I don’t think it a problem with the serial I/O, when I configure a wrong port it’s immediately detected.
But I will check on my side if there is anything.