Weird, I still can’t make this bug show up. Do you and @Colacuve mind uploading the userpref.blend file being used when the error appears?
It will be in Blender’s executable directory if you created a “config” folder here:
Or at somewhere like this (if you’re on Windows 10)
The location will be displayed in the console after you click “Save Preferences” in the Preferences window:
Writing userprefs: C:\Users\USERNAME_HERE\Path\To\blender-2.80-blah\2.80\config\userpref.blend' ok
Another option might be Exporting your Keymap settings. Blender will save them as a “.py” file.
The selecting behavior in Blender was rewritten with the move from Blender Internal to EEVEE and changed something. I’m aware of the issue, but haven’t found a solution yet.