Cannot define a port

I installed 2.0beta6 on Ubuntu 16 - was straight forward - and compiled some scripts. All ok.

But I could not set a port. The only port available is /dev/ttyUSB0 and this is correctly shown under Tools->Port, but clicking on it has no effect. It is not selected. Likewise, using the "Select Other Board & Port" menu entry allows me to click on the correct (and only) port, yet no port is defined.

As a consequence I cannot upload any sketches.

Installed Beta 7 and got the same effect. Tried a dozen times to define a port, yet was no accepted.

After the 3rd restart of beta7, now the port i present, and uploading works. But I see strange Output:

--------------------------
Compilation complete.
Waiting for upload port...
No upload port found, using /dev/ttyUSB0 as fallback

while at the same time the GUI tells me, the ESP and Port are well defined:
Auswahl_011

Do you have the right board selected?

What do you mean? I have included a screenshot showing "ESP32 Dev Module at /dev/ttyUSB0", and this is precisely what I have???

And as I said, it now "defaults" to this setting, and it compiles correctly. It is just that it looks I need to "prime" the IDE by restarting it mutiple times.