Sorry for the previous post: now it seems to be working no uninstalled necessary.
What I did, though not sure what worked:
1) I did restart the program several times and restart my whole computer. (I've got a mac book pro Sierra 10.12.4).
2) I was also trying to select a device that was not physically connected to my laptop.
--so I connected it, that didn't work. I tried using the CLI
particle list and got nothing
3) Plugged in two other photon (physically to my machine: usb), still
4) posted the above
5) opened particle dev again after closing it and now it works
I have no idea what happened, but thankfully no reinstall for now!!!