I suspect that you are having linux permissions issues accessing the device. For Linux machines running udev, like Raspberry Pi OS, you normally add a rule. We provide this rule which works on most machines. Unplug your Joulescope, then do this:
$ wget https://raw.githubusercontent.com/jetperch/pyjoulescope/master/99-joulescope.rules
$ sudo cp 99-joulescope.rules /etc/udev/rules.d/
$ sudo udevadm control --reload-rules
Plug your Joulescope back in, and joulescope info should now find it.