Ok I tried it again in chrome on the same computers and this time it worked. I managed to get connected on all of them. This time I logged out of each one before adding the next. Maybe that did it, or maybe it just needed to be added twice?
@Mdocken this is strange, normally it should not prompt you to register twice on the machine. Maybe there was an issue, like the browser / extension crashed and needed to be restarted. Hard to tell without looking at browser extension error logs. Let us know if that happens again.